cm 


BOILER  PLANT  TESTING 


PLANT    TESTING 

A  CRITICISM  OF  THE  PRESENT  BOILER 
TESTING  CODES  AND  SUGGESTIONS  FOR 
AN  IMPROVED  INTERNATIONAL  CODE 


BY 

DAVID    BROWNLIE 

)v 

B.Sc.  (HONOURS  IN  CHEMISTRY)  LONDON 

Fellow  of  the  Chemical  Society 

Member  of  the  Society  of  Chemical  Industry 

Member  of  the  Society  of  Dyers  and  Colourisfs 

Member  of  the  American  Chemical  Society 

Member  of  the  American  Society  of  Mechanical  Engineers 

Associate  Member  of  the  Institution  of  Mining  Engineers 

Member  of  the  South  Wales  Institute  of  Engineers 

Associate  of  the  Institute  of  Mechanical  Engineers 


NEW   YORK: 

E.    P.   DUTTON    &   CO. 

1922 


B7 


Engineering 
Idbrary 


PRINTED   IN    GREAT    BRITAIN 

AT    THE    ABERDEEN   UNIVERSITY    PRESS 

ABERDEEN,   SCOTLAND 


INTRODUCTION. 

THERE  is  at  present  no  practical  and  definite  Code  in  Great 
Britain  for  boiler  plant  testing,  and,  consequently,  such  tests 
are  largely  carried  out  according  to  the  fancy  of  the  particular 
engineers  engaged.  I  am  decidedly  of  the  opinion  that  the 
time  has  arrived  for  the  adoption  of  a  standard  up-to-date 
Code  devised  on  thoroughly  practical  lines,  especially  in  view 
of  the  urgent  necessity  of  fuel  economy,  and  the  fact  that 
nearly  50  per  cent,  of  the  coal  consumption  of  Great  Britain 
is  used  for  the  one  operation  of  steam  generation. 

What  is  supposed  to  be  the  Standard  Code  in  Great  Britain 
is  that  of  the  Institution  of  Civil  Engineers  ("  Report  of  the 
Committee  on  Tabulating  the  Results  of  Steam  Engine  and 
Boiler  Trials  ".  Revised  191 3.  Published  by  Messrs.  William 
Clowes  &  Sons  Ltd.,  94  Jermyn  Street,  London,  S.W.  i. 
Price  3/-  net). 

The  original  Committee  of  the  Institution  of  Civil  En- 
gineers for  this  purpose  was  appointed  on  the  29th  June,  1897, 
and  they  made  an  Interim  Report  on  the  25th  April,  1901, 
followed  by  a  final  Report  on  the  1 4th  April,  1902.  The 
Committee  was  then  reappointed  on  the  I9th  October,  1909, 
to  revise  the  original  Code  of  1902,  and  the  Report  of  this 
latter  Committee  is  embodied  in  the  present  (1913)  Code.  In 
practice,  however,  this  Code  is  ignored  because  it  is  too  com- 
plicated and  unpractical. 

I  am  of  the  opinion  also  that  the  Code  is  entirely  out-of- 


581122 


vi  INTRODUCTION 

date,  and,  with  all  due  respect  to  the  Institution  of  Civil 
Engineers,  the  devising  of  an  Improved  Code  is  essentially 
the  business  of  two  branches  of  engineering,  chemical  and 
mechanical. 

The  Standard  Code  in  America-'for  Boiler  Plant  Testing  is 
the  "  Rules  for  Conducting  Performance  Tests  of  Power  Plant 
Apparatus,  Code  1915,"  of  the  American  Society  of  Mechan- 
ical Engineers,  29  West  Thirty-ninth  Street,  New  York, 
U.S.A.,  being  the  Report  of  the  Power  Test  Committee, 
which  resulted  from  the  Council's  resolution  of  1 3th  April, 
1909.  As  is  of  course  well  known,  this  Code  is  at  present 
under  revision  by  the  "  Power  Individual  Committee,  No.  4  n 
(Messrs.  E.  R.  Fish  (Chairman),  D.  D.  Pratt  (Secretary), 
A  D.  Bailey,  W.  N.  Best,  A.  A.  Carey,  and  E.  B.  Ricketts), 
and  by  the  courtesy  of  the  Secretary  I  have  been  able  to  study 
the  preliminary  draft  of  the  Report  of  this  Committee,  so  that 
any  criticisms  and  remarks  of  mine  in  this  book  apply  to  the 
Final  Revised  Code.  I  think  that  this  American  Code,  even 
as  revised  by  the  "  Power  Individual  Committee,  No.  4,"  is 
still  open  to  criticism,  although  much  superior  to  the  British 
Civil  Engineers'  Code. 

I  suggest,  therefore,  that  the  time  is  ripe  for  the  devising  of 
a  Standard  International  Boiler  Testing  Code  by  the  American, 
British  and  French  Engineering  and  Scientific  Societies  work- 
ing in  collaboration. 

In  Great  Britain  the  premier  societies  concerned  are  the 
Institution  of  Mechanical  Engineers  and  the  Institution  of 
Chemical  Engineers,  with  various  other  societies  like  the 
Civil  Engineers,  Electrical  Engineers,  Mining  Engineers,  and 
the  Society  of  Chemical  Industry,  holding  a  watching  brief. 
In  America  the  lead  would  presumably  be  taken  by  the 
American  Society  of  Mechanical  Engineers,  and  in  France  by 
the  Ingenieurs  Civils  de  France. 


INTRODUCTION  vii 

The  present  book  is  a  contribution  towards  the  work  of 
devising  such  an  improved  International  Code,  and  I  have 
divided  it  into  the  following  parts : — 

Part  I. — "The  Results  at  present  being  obtained  on 
Boiler  Plants  in  General,"  to  show  the  necessity  of  adopting 
modern  scientific  methods  in  steam  generation,  and  of  devising 
a  practical  international  test  Code  to  encourage  such  work. 

Part  II. — "Criticisms  of  Existing  Codes  and  Suggestions 
for  Improvement."  This  part  is  divided  under  the  following 
heads : — 

1.  The   necessity    of   a   separate   Code   for   boiler    plant 
testing. 

2.  The1  object  of  boiler  plant  testing. 

3.  Duration  of  test. 

4.  Sampling  and  analysis  of  the  fuel. 

5.  Flue  gas  analysis. 

6.  The  method  of  measuring  the  boiler  feed-water. 

7.  Moisture  in  the  steam. 

8.  Specific  heat  of  superheated  steam. 

9.  Steam  or  power  used  auxiliary  to  the  production  of 
steam. 

10.  Lbs.    of  water    from    and   at   212°   F.   per    1,000,000 
B.Th.U. 

11.  Various  minor  points. 

12.  The  method  of  calculating  the  results. 

All  these  points  are  matters  that  could  be  settled  imme- 
diately by  American,  British  and  French  Committees  appointed 
to  devise  the  International  Code,  and  would  include  the  pro- 
vision of  a  list  of  "  recommended  "  instruments,  calorimeters, 
water  meters,  combustion  recorders,  pyrometers,  etc. 

Part  III. — "  Suggestions  for  New  Features  that  may  be 
added  in  the  future  to  an  International  Code  as  the  result  of 
further  discussion  and  investigation."  This  chapter  includes 


viii  INTRODUCTION 

the  following  heads,    and   consists  of  various  matters  which 
may,  or  may  not,  be  added  to  an  International  Code : — 

1.  The  question  of  the  use  of  a  special  factor  depending  on 
the  quality  of  the  fuel. 

2.  Labour,  attendance,  repairs,  upkeep,  interest,  and  de- 
preciation. 

3.  Dust  and  grit  in  the  chimney  gases. 

4.  Steam  meters. 

Part  IV. — "  Design  of  a  New  and  Improved  Code  as  a 
suggested  basis  for  the  International  Code,"  giving,  as  an 
example,  the  results  of  an  actual  boiler  test  according  to  the 
suggested  Code. 

For  convenience  and  simplicity,  throughout  this  book,  the 
fuel  under  discussion  is  coal ;  but  the  same  reasoning  and 
principles  will  apply  to  all  fuels,  solid,  liquid,  and  gaseous. 

The  general  grounds  for  criticism  of  the  Institution  of 
Civil  Engineers'  Code,  in  particular,  I  consider  to  be  as 
follows : — 

1.  The    Code  is  far  too  academic   and   not  adapted    to 
practical  requirements,  and  it  appears  to  be  drawn  up  with' 
the  idea  that  boiler  tests  are  a  luxury  only  to  be  carried  out 
on  rare  occasions.     Thus  it  takes  up  pages  arguing  about  heat 
balance  sheets,  specific  heat  of  flue  gases,  and  the  full  chemi- 
cal analysis  of  the  fuel,  and  almost  ignores  matters  of  vital 
practical  importance,  such  as  the  amount  of  auxiliary  steam 
or  power  used  on  the  plant,  the  price  of  the  fuel,  and  the  cost 
of  evaporation  of  a  unit  of  water. 

2.  The  Code  is  completely  out-of-date  in  the  methods  given 
for  carrying  out  the  test.     For  example,  it  insists  on  weighing 
or  measuring  the  water  in  tanks,  even  at  sea,  and  practically 
omits  to  mention  the  twenty  different  water  meters  available, 
and  also  does  not  discuss  steam  meters.     Although  it  insists 


INTRODUCTION  ix 

rightly  on  a  bomb  calorimeter  for  fuel  analysis,  it  recommends 
an  instrument  no  one  in  this  country,  except  the  "  Civils  " 
Committee,  has  ever  heard  of,  and  as  regards  flue  gas  analysis, 
hand  methods  of  the  most  antiquated  and  unpractical  types 
are  insisted  upon.  Automatic  CO2  Recorders,  a  commonplace 
of  modern  boiler  plant  work,  are  disparaged,  but  if  used,  an 
instrument  is  recommended  which  is  many  years  out-of-date. 

3.  The  Code  is  expressed  in  such  a  confused  and  compli- 
cated manner  that  it  rivals  the  Income  Tax  and  can  only  be 
understood  with  great  difficulty,  whilst  the  methods  of  calcu- 
lating the  results  are  so  intricate  as  to  be  largely  unintelligible 
without  a  great  effort,  even  to  specialists  on  the  subject.  Thus 
it  is  not  drawn  up  in  any  logical  sequence.  The  first  sheet 
deals  with  "  General  Description  of  the  Boiler,"  and  then  the 
second  sheet  follows  with  data  from  the  test.  We  then  come 
to  "  General  Description  of  the  Economiser  and  Superheater," 
and  in  this  way  general  descriptive  matter,  data,  and  calcula- 
tions are  all  mixed  up  together  in  the  most  extraordinary 
manner.  The  attempt  also  to  regard  the  boiler,  economiser 
and  superheater  as  entirely  separate  is  most  confusing. 

I  have  to  confess  that,  if  only  because  of  the  continual 
cross  references,  I  have  been  compelled  to  buy  a  number  of 
copies  of  the  Code  and  cut  them  up  with  scissors,  so  that 
all  the  references  to  each  point  could  be  stuck  on  one  large 
sheet  of  paper,  and  in  this  way  to  dissect  the  Code  into  a 
large  number  of  separate  sheets,  so  as  to  read  it  easily.  For 
example,  the  question  of  auxiliary  steam  or  power  has  five 
different  references,  and  the  particulars  relating  to  the  calcula- 
tions based  on  the  full  chemical  analyses  of  the  fuel  and  the 
flue-gases  are  hopelessly  involved.  The  American  Mechan- 
icals Code  is  infinitely  superior  in  this  respect,  and  is  provided 
with  an  admirable  index. 

In  studying  the  Civils  Code  at  great  length,  one  is  com- 

6 


x  INTRODUCTION 

pelled  to  come  to  the  conclusion  first,  that  it  applies  only,  more 
or  less,  to  the  years  1897-1901,  the  time  of  its  original  forma- 
tion— and  little  alteration  seems  to  have  been  made  in  1913, 
so  that  it  is  about  twenty  years  out-of-date — and  secondly, 
that  the  Committee  apparently  have  had  in  mind  only  academic 
tests  on  small  boiler  plants  of  one  boiler  or  so.  The  attempts 
to  apply  the  Code  to  moderate  sized  boiler  plants,  and  espe- 
cially to  very  large  plants,  like  twenty  "  Lancashire"  boilers  or 
equivalent,  prove  it  to  be  ludicrously  unpractical,  as  I  hope  to 
show. 


D.  BROWNLIE. 


2  AUSTIN  FRIARS, 
LONDON,  E.G.  2. 
March,  1922. 


CONTENTS. 

PAGE 

INTRODUCTION      ....  v 

PART  I. 
THE    RESULTS    AT    PRESENT   BEING    OBTAINED   ON    BOILER 

PLANTS  IN  GENERAL    .         .         ....         .         i 

PART  II. 
CRITICISMS  OF  EXISTING  CODES   AND   SUGGESTIONS  FOR  AN 

IMPROVED  INTERNATIONAL  CODE  .         .  .'        .       49 

PART  III. 

SUGGESTIONS  FOR  NEW  FEATURES  WHICH  MAY  BE  ADDED  IN 
THE  FUTURE  TO  AN  INTERNATIONAL  CODE  AS  THE  RESULT 
OF  FURTHER  DISCUSSION  AND  INVESTIGATION  .  .124 

PART  IV. 
DESIGN  OF  REPORT  SHEETS  FOR  THE  NEW  CODE         .         .     133 

SUMMARY     .....  ....     153 

INDEX          .        ,.         .  .      .         .     ^  .         .         .         .         .     157 


PART  I. 

THE    RESULTS   AT   PRESENT   BEING   OBTAINED 
ON  BOILER  PLANTS  IN  GENERAL. 

THE  new  Code  suggested  in  this  book  as  a  basis  for  an  Inter- 
national Code  is  the  result  of  fifteen  years'  continuous  experi- 
ence of  boiler  plant  testing,  comprising  several  thousand 
tests,  during  which  time  the  methods  of  testing,  and  calcula- 
tion, used  have  been  gradually  altered  and  improved  until 
the  Code  has  arrived  at  its  present  form. 

There  has  not  hitherto  been  much  reliable  information 
available  as  to  the  actual  results  being  obtained  in  practice 
from  week  to  week  on  the  boiler  plants  of  Great  Britain. 
Much  of  the  data  obviously  only  applies  to  special  test  con- 
ditions, where  everything  is  particularly  favourable,  especially 
as  regards  attention,  quality  of  fuel  used,  rate  of  evaporation, 
repair  of  brickwork,  etc.,  for  obtaining  the  best  results,  and 
such  data  gives  an  entirely  false  impression  as  to  the  real 
figures  that  are  being  obtained  in  practice. 

Thus  Donkin,  in  his  book  "  Heat  Efficiency  of  Steam 
Boilers,"  gives  fifty  tables  containing  the  results  of  425  ex- 
periments on  different  boilers.  These  results  are  summarised 
on  page  2  (being  for  the  boilers  only,  without  economisers). 

The  figures  are,  in  my  opinion,  very  much  too  high  for 
average  working  conditions.  It  will  be  noted  that  they 
apply  to  boilers  only,  without  economisers  and  superheaters, 
and  we  have  extraordinary  results  like  72  per  cent,  efficiency 
for  ten  experiments  on  a  "  Lancashire  "  boiler  only,  whereas 
107  experiments  on  a  "  Lancashire"  boiler  showed  62-4  per 


,  Ft  A  NT  TESTING 

cent,  which  is  still  a  very  high  figure,  and  such  as  could  only 
be  obtained  with  the  best  attention.  These  figures,  however, 
show  the  great  variation  being  obtained,  and  in  107  "Lanca- 
shire" boiler  tests,  for  example,  we  have  figures  from  42-1  to 
79'5  per  cent,  efficiency.  -  ,  ^ 


Type  of  Boiler. 

No.  of  Ex- 
periments. 

Average 
Efficiency. 

Average  of 
Two  .Best 
Results. 

Worst 
Result. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Water-tube,  i^-in.  tube 

6 

77*4 

84T 

66-6 

Locomotive 

37 

72-5 

83'3 

53'7 

Lancashire 

10 

72-0 

74'4 

65-6 

Two-storey 

9 

7°'3 

76-I 

57-6 

ji                •         • 

29 

69-2 

79-8 

55'9 

Dry  back 

24 

69-2 

757 

647 

Return  tube 

ii 

687 

81*2 

56-6 

Cornish     . 

25 

68-0 

817 

53'o 

... 

9 

67-0 

8ro 

55'o 

Wet  back 

6 

66-0 

69-6 

62*0 

Elephant  . 

7 

65-3 

70-8 

58-9 

Water-tube,  4-in.  tubes 

49 

64-9 

77'5 

50*0 

Lancashire 

40 

64-2 

73-0 

5i-9 

Cornish    . 

3 

627 

65'9 

6o'o 

Lancashire 

107 

62*4 

79'5 

42-1 

Dry  back  . 

6 

61*0 

73*4 

54*8 

Lancashire,  3-flue     . 

6 

59'4 

66-7 

52-0 

Elephant  . 

8 

58'5 

65*5 

54'9 

Lancashire 

8 

57'3 

74'3 

45'9 

Vertical     . 

5 

56-2 

76-5 

44-2 

W.  S.  Hutton,  in  his  book,  "Steam  Boiler  Construction" 
,  gives  data  for  the  performance  of  various  types  of 
boilers  "  which  may  generally  be  obtained  in  practice  with 
boilers  having  tolerably  clean  heating  surfaces,  when  fired 
with  good  coal,"  as  follows : — 


Type  of  Boiler. 

No.  of 
Tests  Given. 

Evaporation.     Pounds  of  Water 
from  and  at  212°  F. 

Lancashire 

22 

8-25  to  12*02 

Cornish 

7 

7*75  »»  11*56 

Egg-ended  . 

6 

6-52  „    8-56 

Vertical 

15 

5'57    „    10-21 

Water-tube 

73 

7-02  ,,  13*40 

RESULTS  AT  PRESENT  BEING  OBTAINED      3 
Again,  some  figures  supplied  by  Molesworth : — 


Description  of  Boiler. 

Pounds  Water  from  and 
at  212°  F.  Evaporated 

Per  Lb.  Average  Coal. 

Egg-ended 

8-0 

Cornish 

8-0 

Lancashire 

9-0 

Water-  tube 

8-0 

Ordinary  Marin 

9'5 

Tubular      . 

9'5 

Locomotive 

10-5 

Torpedo  boat 

13-0 

Andre  states  that  I  Ib.  of  the  coals  mentioned  will  evapor- 
ate, under  ordinary  practical  conditions,  the  following  amounts 
of  water  : — 


Quality  of  Coal. 

Evaporation. 
Pounds  of  Water  from 
and  at  212°  F. 

Gaseous  coals 
Bituminous-fuliginous 
Flaming 
Clear  burning          .                  . 
Semi-bituminous     . 
Anthracite 

6-25 
8-00 
8-75 

9-10 
9-20 

A  particularly  ludicrous  statement,  in  a  recent  (1920) 
"  Chemical  Pocket  Book,"  is  as  follows  : — 

"  The  efficiency  of  a  boiler  should  be  as  near  to  80  per 
cent,  as  possible,  this  figure  being  considered  excellent.  A 
more  usual  figure  is  70  per  cent,  which  is  quite  good.  The 
water  from  and  at  212°  F.  per  Ib.  of  combustible  is  a  good 
indication  of  the  efficiency  of  a  boiler,  and  under  normal  con- 
ditions should  be  about  12-0  Ibs." 

In  general,  and  quite  apart  from  academic  absurdities,  it 
is  not  realised  how  bad  are  the  figures  for  the  average  boiler 
plant.  Thus,  among  practical  engineers,  it  is  usual  to 
assume  that  I  Ib.  of  average  coal  evaporates  7  to  8  Ibs.  of 
water  from  and  at  212°  F.,  and,  for  example,  most  engine 
builders  take  a  figure  of  8'O  Ibs.  in  calculating  the  steam 


4  BOILER  PLANT  TESTING 

consumption  of  their  engines  and  the  size  of  boiler  plant 
necessary.  In  my  experience  such  figures  are  much  too  high. 
Some  of  the  present  authorities  are  also  of  this  opinion,  and, 
for  example,  the  figures  given  in  Kempe  ("Engineers'  Year 
Book,  1920  ")  are  as  below  :  —  L 


Description  of  Boiler. 

Small  cylindrical  boiler  (no  economisers)          .         .         .  45  to  55 

Large  cylindrical  boiler  with  economiser          .         .         .  60  ,,  70 

Small  water-  tube      ,,         „             ,,                   .         .         .  50  „  60 

Large          „          .  .»         »             »»          •  7« 

In  very  good  condition     .......  70  to  75 

Locomotive  boiler,  moderately  fired          .         .         .         .  65  ,,  70 

Marine  boiler,  well  fired           ......  60  ,,  70 

Most  of  the  exaggerated  opinions  as  to  the  figures  for  the 
performance  of  steam  boiler  plant  seem  to  be  due  to  the  fact 
that  it  is  not  realised  how  important  is  the  quality  of  the  fuel. 
The  performance  figures  of  any  boiler  plant  depend  largely 
on  this  point.  Thus,  as  I  will  discuss  in  detail  later,  if  a  coal 
of  12,000  B.Th.U.  deteriorates,  say  10  per  cent.,  to  10,800 
B.Th.U.,  the  loss  in  evaporation  in  practice  is  much  more  than 
10  per  cent.  The  difficulties  caused  by  the  accumulation  of 
ash,  and  the  reduction  of  radiant  heat  causes  a  much  greater 
drop  in  evaporation  than  that  corresponding  to  the  mere  reduc- 
tion in  heating  value,  and  the  net  reduction  is,  say,  15  per 
cent,  to  I7-J  per  cent,  instead  of  10  per  cent. 

In  the  same  way,  an  increase  in  heating  value  of  10  per 
cent,  say  from  12,000  B.Th.U.  to  13,200  B.Th.U.,  gives  more 
than  the  mere  10  per  cent,  increase  in  heating  value,  because 
of  the  greater  freedom  from  ash  and  the  increased  radiant 
heat.  These  facts  must,  therefore,  be  borne  in  mind  in  con- 
sidering the  figures  given  on  the  different  types  of  plants. 

For  example,  Bryan  Donkin  and  A.  B.  W.  Kennedy  pub- 
lished, in  1897  ("  Experiments  on  Steam  Boilers,"  Offices  of 
"  Engineering  "),  the  results  of  a  series  of  experiments  on  the 
performance  of  a  number  of  types  of  steam  boilers  comprising 
twenty-one  separate  determinations,  and  including  "  Vertical," 
"  Tubular,"  "  Lancashire,"  "  Locomotive,"  "  Water-tube," 


RESULTS  AT  PRESENT  BEING  OBTAINED      5 

"  Cornish,"  "Cornish  Multi-tubular  "  and  "Elephant"  boilers. 
These  experiments,  however,  do  not  give  us  much  data  of 
practical  value,  because  they  were  carried  out  under  ideal  con- 
ditions with  coal  of  extraordinarily  good  quality,  namely,  the 
finest  Welsh  steam  coal.  Thus  the  heating  value  of  the  dried 
coal  was  no  less  than  15,560  B.Th.U.  per  pound,  with  only 
3  per  cent,  ash,  and  the  theoretical  evaporation  of  I  Ib.  of 
the  dried  coal  from  and  at  212°  F.  was  given  as  i6'i  Ibs.  of 
water.  As  typical  of  the  figures  obtained,  a  "Lancashire" 
boiler  gave  70*4  per  cent,  efficiency  without  economisers,  and 
9-92  Ibs.  of  water  evaporation  per  pound  of  coal.  A 
"  Cornish  "  boiler  showed  78*3  per  cent,  efficiency  with  1 1 '4 
Ibs.  of  water  from  and  at  212°  F.  per  pound  of  coal,  whilst  a 
"water-tube"  boiler  showed  74-4  per  cent,  efficiency  and 
9-90  Ibs.  of  water  per  pound  of  coal. 

These  results  obviously  only  apply  to  purely  abnormal 
conditions,  and  are  of  little  use  in  arriving  at  average  figures 
for  boiler  plants  as  generally  working  in  industry. 

The  firm  with  whom  I  am  associated  have  been  engaged 
continuously  for  the  past  dozen  years  or  so  in  carrying  out 
complete  scientific  investigations  into  the  working  of  steam 
boiler  plants  in  Great  Britain,  and  also  in  reorganising  existing 
plants  or  erecting  new  plants.  From  1908  to  the  present  time 
we  have  tested  nearly  500  different  boiler  plants,  with  a  total 
annual  coal  bill  of  about  4,000,000  tons,  and  made  a  personal 
examination  (without  testing)  of  about  2000  plants  with  a 
total  coal  bill  of  about  15,000,000  tons  per  annum. 

I  have  at  the  present  time  the  tabulated  results  of  the 
complete  scientific  investigation  of  400  different  boiler  plants, 
wish  a  total  coal  bill  of  3,250,000  tons  per  annum,  the  number 
of  boilers  being  1513,  in  forty-one  different  industries,  as 
detailed  on  page  6. 

Before  discussing  the  results  obtained,  I  should  like  to 
give  a  short  account  of  the  methods  used  in  carrying  out  the 
tests,  which  were  in  each  case  of  the  most  comprehensive 
character,  and  not  a  mere  inspection  and  expression  of  opinion 


6  BOILER  PLANT  TESTING 

in  the  sense  used  by  certain  Fuel  Economy  Associations  or 
Organisations. 

A  detailed  test  of  the  plant  was  made  first  for  one  work- 
ing day,  and  a  further  test  for  one  week  was  carried  out  as  a 

Number  of 
Industry.  Plants  Tested. 

Aniline  dye  manufacturers 4 

Breweries 5 

Calico  printers 10 

Carpet  manufacturers 6 

Cement              ,,                 i 

Collieries  (including  several  steel  works)  .         .112 

Cotton  bleaching 9 

„      mills 23 

,,      piece  dyeing 18 

,,      yarn        „                9 

Dyeing  and  cleaning 8 

Electricity  station i 

Engineering 10 

Explosives 27 

Fine  organic  chemicals     .         .         .         ...         .  3 

Flour  mills 4 

Food  products 3 

Glue  manufacturers 8 

Hat             „              3 

Heavy  inorganic  chemicals 7 

Hosiery  mills 5 

„       dyeing 4 

Hospitals J 

India-rubber  manufacturers 5 

Jute  mills * 

Lace    „ 7 

,,     bleaching 3 

Laundries          .         .         .         .         .         •         •         •  * 

Linen  mills       . 2 

Paint  manufacturers i 

Paper  mills       ....       V         ...  41 

Potteries I         ...  4 

Pumping  station        .                  i 

Residential  mansions i 

Soap  manufacturers 3 

Silk  dyeing  and  printing 2 

Tanneries 7 

Textile,  special ! 

Woollen  mills  . '  < 36 

„        yarn  dyeing i 

Total         .         .         .  400 

check  on  the  figures  for  the  fuel  used  and  the  water  evaporated, 
and  to  ascertain  the  weekly  conditions,  including  all  week-end 
losses  due  to  stoppage  of  plant,  etc. 

It  will  be  clearly  understood  that  the  object  of  these  tests 


RESULTS  AT  PRESENT  BEING  OBTAINED   7 

was  to  find  out  the  exact  normal  everyday  working  conditions 
of  the  plant,  particularly  as  regards  efficiency  and  the  cost  in 
coal  for  the  production  of  a  unit  of  steam  (evaporation  of 
1000  gallcfns  of  water),  so  that  a  scheme  of  reorganisation 
could  be  devised  for  the  more  economical  production  of  steam — 
that  is  to  say — these  figures  represent  the  true  performance  of 
the  plants  as  run  from  week  to  week,  and  the  boiler-house 
staff  worked  the  plant  as  usual. 

In  carrying  out  the  tests,  the  water  level  in  the  boilers 
and  the  general  condition  of  the  fires  was  the  same  at  the  end 
as  at  the  commencement  of  the  test.  With  regard  to  the 
details  of  the  carrying  out  of  the  tests  we  have  : — 

Weight  of  Fuel  Used. — This  was  determined  in  the 
usual  various  ways,  depending  on  the  circumstances  of  the 
case,  from  weighing  the  fuel  in  barrows  or  bags,  to  weighing 
carts  and  railway  trucks  direct. 

Analysis  of  Fuel. — As  is  well  known,  it  is  an  extremely 
difficult  matter  to  get  a  thoroughly  average  sample  of  coal, 
especially  when  there  is  variation  in  the  quality,  and  we  took 
the  greatest  care  in  this  respect.  Samples  were  taken  every 
half-hour  by  the  clock,  and  also  every  hour  and  placed  in 
separate  receptacles.  At  the  end  of  the  trial  the  accumulated 
hourly  and  half-hourly  samples  were  broken  up,  thoroughly 
mixed,  quartered,  and  so  on,  as  usual,  several  pounds  being 
finally  taken  in  sealed  tins  for  analysis.  There  were  thus 
obtained  two  entirely  independent  samples  of  the  same  fuel. 
In  the  same  way  we  took  samples  of  coal  every  day  during 
the  long  check  test  as  a  check  on  the  figures  for  the  day. 
The  two  days'  samples  were  then  analysed  separately,  and 
the  average  figures  taken.  If  more  than  one  quality  of  fuel 
was  used  on  the  test,  each  separate  quality  had  two  independent 
samples  taken  as  above  described,  so  that  in  some  cases  on  a 
day's  trial  as  many  as  six  different  samples  were  analysed  and 
the  results  averaged. 

As  regards  the  analysis  of  the  coal,  the  heating  value  was 
determined  by  means  of  an  oxygen  bomb  calorimeter 


8  BOILER  PLANT  TESTING 

("  Mahler-Donkin  ").  The  bomb  type  of  calorimeter  is,  of 
course,  acknowledged  to  be  the  standard  scientific  instrument 
for  accurate  heat  determination,  and  the  method  consisted  in 
burning  the  damp  fuel  (as  fired)  in  a  platinum-lined  gunmetal 
bomb  in  oxygen  at  about  450  Ibs.  pressure  per  sq.  in. 
The  ignition  is  made  inside  the  "bomb  by  means  of  a  fine 
platinum  wire  heated  by  outside  electric  contact.  If  platinum 
wire  was  not  obtainable,  fine  iron  wire  was  used,  and  a  correction 
made  for  the  heat  of  combustion  of  the  iron  to  iron  oxide. 
The  bomb  is  covered  with  a  known  amount  of  water  at  a 
known  temperature,  and  after  ignition  the  rise  in  temperature 
observed  with  a  thermometer  graduated  to  T^V  C.  As  the 
combustion  is  instantaneous  and  totally  enclosed,  the  heating 
value  is  obtained  direct  without  any  corrections  being  required. 
Further,  the  combustion  is  always  complete,  which  is  not  the 
case  with  many  inferior  types  of  calorimeter. 

As  I  will  discuss  later  in  detail,  there  is  much  confusion 
with  regard  to  the  method  of  expressing  the  results.  In  a 
bomb  calorimeter  of  this  description  the  moisture  in  the  coal, 
and  the  moisture  formed  by  the  combustion  of  the  (organic) 
hydrogen  in  the  coal,  are  driven  off  as  steam  and  condensed 
again  in  the  bomb,  so  that  the  whole  of  the  heat  is  retained 
and  included  in  the  heating  value.  In  actual  practice,  how- 
ever, when  the  coal  is  thrown  into  the  furnace,  the  water  is 
driven  off  as  steam  and  tends  to  escape,  and  to  pass  away  in 
the  chimney  base  at  the  same  temperature  as  the  gases,  say, 
at  an  average  of  400°  F.  Thus  the  gross  heating  value  as 
obtained  by  the  bomb  is  slightly  higher  than  the  real  heating 
value  that  would  be  obtained  in  practice  because  of  this 
loss  of  heat  due  to  steam  escaping  in  the  gases.  In  view  of 
these  difficulties  I  have,  in  each  case,  taken  the  higher  or 
gross  heating  value,  that  is,  the  heating  value  as  actually 
obtained  by  the  combustion  of  the  damp  coal  in  the  bomb 
calorimeter. 

With  regard  to  the  percentage  of  ash,  this  was  determined 
by  complete  combustion  in  the  muffle  furnace,  so  that  the 


RESULTS  AT  PRESENT  BEING  OBTAINED   9 

figures  given  for  the  amount  of  ash  represent  the  real  non- 
combustible  matter,  not  allowing  for  any  slight  loss  that  might 
take  place  by  the  volatilisation  of  a  portion  of  the  ash.  The 
percentage  of  ash  obtained  from  the  boiler  plant  will,  of  course, 
always  in  practice  be  slightly  higher,  as  it  is  impossible  to 
obtain  complete  combustion  of  the  ashes,  and  under  good 
average  conditions  there  is  always,  say,  I  to  2  per  cent,  of 
combustible  matter  in  the  ash  as  thrown  away  on  the  ash 
dumps.  I  may  say,  however,  that  in  scores  of  boiler  plants, 
there  is  a  big  loss  in  this  direction,  and  it  is  quite  possible  to 
find  as  much  as  5  per  cent,  or  even  up  to  10  per  cent,  of 
combustible  matter  still  retained  in  the  ash.  I  have  actually 
come  across  several  instances  where  one  works  has  bought 
ashes  from  another  works  for  road-making,  etc.,  and  then  used 
these  ashes  as  fuel  under  the  boilers. 

Water  Evaporated. — Various  methods  were  used,  de- 
pending on  circumstances,  to  measure  the  water  evaporated, 
but  generally  the  method  adopted  was  the  use  of  a  well-known 
make  of  pressure  type  hot-water  meter  calibrated  before  each 
test,  and  working  between  the  boiler  feed  pump  and  the 
economisers. 

Moisture  in  Steam. — Another  difficulty,  which  I  will 
discuss  in  detail  later,  in  boiler  plant  testing  is  the  fact  that 
non-superheated  steam  always  contains  a  certain  amount  of 
moisture,  varying  from  o  to  5  per  cent,  apart  from  priming, 
that  is  water  from  the  boiler  plant  which  has  not  been  con- 
verted to  steam.  Theoretically,  therefore,  the  amount  of 
moisture  in  the  steam  should  be  determined  and  this  amount 
deducted  (with  suitable  temperature  allowances)  from  the 
evaporation  in  calculating  the  true  performance  of  the  boiler 
plant  The  practical  difficulties  in  the  way  of  this  are, 
however,  very  great,  and  on  this  account,  most  boiler  tests 
are  carried  out  without  determining  the  moisture  in  the 
steam,  and  we  have  followed  the  general  practice  in  this 
respect. 

Analysis  of   Feed- Water. — Samples   of  the    feed-water 


io  BOILER  PLANT  TESTING 

were  taken  every  half-hour  during  the  day's  test,  and  good 
average  samples  obtained  in  this  way.  The  samples  were 
analysed  by  the  "  Wanklyn  "  soap  test  method  before  and  after 
boiling,  giving  the  permanent  and  temporary  hardness, 
although  in  exceptional  cases  the  lull  scientific  analysis  of  the 
feed-water  was  carried  out  in  the  usual  lines  to  determine  the 
parts  per  100,000  of  calcium  and  magnesium  bicarbonate  and 
sulphate,  including  the  total  solids,  etc.  I  may  say  that  in 
my  experience  the  scap  test  is  a  very  convenient  method, 
although  somewhat  despised  by  most  chemists. 

Temperature  of  Feed-Water. — On  the  day's  test,  the 
temperature  of  the  feed-water,  before  and  after  the  economisers, 
was  taken  every  half-hour,  or  oftener  if  the  variation  was  con- 
siderable. For  this  purpose  we  generally  used  calibrated 
mercurial  thermometers,  as  the  ordinary  economiser  ther- 
mometers supplied  with  economisers  are  not  very  accurate 
after  months  of  work. 

Draught  Measurement.— On  the  day's  test  the  draught 
was  taken  every  half-hour,  in  various  convenient  positions  on 
the  boiler  plant,  such  as  the  side  flues  of  "  Lancashire  "  boilers, 
the  main  flues,  chimney  base,  before  and  after  the  economisers, 
and  other  similar  positions.  A  |-in.  wrought-iron  pipe  was 
inserted  into  the  middle  of  the  flues  in  each  case,  and  the 
draught  taken  with  an  ordinary  draught  gauge  of  the  glass 
"  U  "  tube  type. 

Temperature  of  the  Flue  Gases. — For  this  determination 
a  well-known  make  of  pyrometer  was  used,  of  the  thermo- 
electric type,  with  platinum-iridium  and  platinum  junction,  in 
a  porcelain  tube  enclosed  in  a  steel  tube,  and  connected 
through  standardised  coils  of  wire  to  a  voltmeter  graduated 
direct  from  212°  to  1500°  F.  The  instrument  was  arranged 
with  a  two-way  switch,  two  coils  of  wire,  and  pyrometers  in 
the  flue  before  and  after  the  economiser,  so  that  the  two  read- 
ings could  be  taken  practically  simultaneously.  Before  each 
test  the  instruments  were  calibrated  by  determining  the  boil- 
ing-point of  some  substance  of  high  boiling-point,  such  as 


RESULTS  AT  PRESENT  BEING  OBTAINED     11 

aniline,  using  for  the  purpose  a  special  form  of  iron  condenser. 
As  usual,  on  the  day  test  the  readings  were  taken  every  half- 
hour. 

Percentage  of  CO2  in  Flue  Gases. — In  each  case  some 
reputable  make  of  Combustion  Recorder  was  fitted  on  the  plant, 
and  the  percentage  of  CO2  recorded  at  the  rate  of  about  20 
analyses  per  hour  on  a  chart,  along  with  the  time  of  the 
analysis.  One  week's  run  was  taken  in  this  way  in  each  case. 
Samples  of  the  gas  were  taken  from  the  side  flues  or  the 
downtake  of  each  boiler  in  rotation,  allowing  as  a  rule  about 
twelve  hours  (say  240  analyses)  on  each  boiler,  so  that  at  the 
end  of  a  week  a  very  good  average  was  obtained.  We  also  in 
many  cases  fitted  up  an  apparatus  for  taking  a  large  volume 
of  the  flue  gases,  say  I  5  to  20,000  c.c.,  very  slowly  during  the 
whole  day's  test,  so  that  at  the  end  of  the  trial  this  1 5  to  20,000 
c.c.  represented  fairly  the  average  during  the  day.  The 
apparatus  was  then  taken  to  our  laboratories  and  the  contained 
gas  analysed  by  means  of  the  "  Orsat  "  apparatus  to  determine 
the  percentage  of  CO  (carbon  monoxide)  after  the  CO2  and 
the  oxygen  had  been  absorbed  in  the  usual  way. 

Steam  Pressure. — On  the  day's  test  the  steam  pressure 
was  taken  every  half-hour,  or  oftener  if  there  was  a  consider- 
fluctuation. 

Temperature  of  Superheated  Steam. — On  the  day's  test 
the  temperature  of  the  superheated  steam  was  taken  every 
half-hour  with  a  calibrated  mercurial  thermometer,  as,  like 
economiser  thermometers,  the  thermometers  in  continuous  use 
with  superheaters  are  seldom  very  accurate. 

Auxiliary  Steam, — With  regard  to  the  steam  or  power 
used  as  auxiliary  to  the  production  of  steam,  in  the  case  of  an 
engine,  the  indicated  horse-power  of  the  engine  was  taken,  and 
from  the  type  of  engine  in  use  a  very  good  idea  was  obtained 
of  the  amount  of  steam  used.  Thus,  for  the  ordinary  enclosed, 
forced-lubrication,  high-speed  engine  for  driving  forced  or 
induced  draught  fans,  an  average  figure  is  35  Ibs.  of  steam 
per  indicated  horse-power.  In  the  case  of  a  motor  drive  the 


12  BOILER  PLANT  TESTING 

power  used  is,  of  course,  very  easily  determined  by  measuring 
the  amps,  and  the  volts.  The  real  difficulty  is  in  connection 
with  the  amount  of  steam  used  in  the  form  of  steam  jets  either 
under  or  over  fire-bars,  and  for  this  we  used  the  special 
apparatus  described  later  (p.  107). 

•* 


Unfortunately,  I  cannot  give  the  detailed  figures  for  the 
performance  of  each  of  the  400  plants,  since  the  amount  of 
space  occupied  by  such  a  mass  of  figures  would  be  outside  the 
limits  of  this  book. 

In  the  first  place,  however,  the  true  average  net  working 
efficiency  of  the  whole  of  the  400  tests  ?s  58  per  cent.,  and  I  feel 
sure  that  these  can  be  taken  as  thoroughly  representative  of 
the  boiler  plants  of  Great  Britain,  since,  in  addition  to  this 
large  numbers  of  tests  carried  out  in  many  different  industries, 
the  2000  plants  we  have  inspected,  representing,  as  already 
stated,  a  coal  bill  of  15,000,000  tons  per  annum,  were  all 
found  to  be  working  on  the  same  general  lines. 

The  figures  can  be  divided  as  follows,  the  highest  individual 
plant  being  82-21  per  cent,  and  the  lowest  32*50  per  cent: — 

Net  Working  Efficiency.  No.  of 

(Boilers,  Economisers  and  Superheaters.)  Plants. 


i.  80  pe 
2.  75  , 
3-  7°  > 

r  cer 

it.  and  ov 

er  .    .    .    .    .    .    .    2 

•   .»    ;    •    •    •    •    9 

4-  65  , 
5.  60  , 

6.  55  , 
7  50 

i 

»>   i 

58 
69 
96 
80 

8.  Below  50  per  cent. 

69 

Total        .         .         .     400 

I  gave  ("Coal  Saving  by  the  Scientific  Control  of  Steam 
Boiler  Plants,"  "Engineering,"  I2th  and  ipth  July,  1918)  the 
true  average  figures  for  250  of  these  plants  (1000  boilers 
and  2,166,000  tons  of  coal  per  annum)  as  follows  : — 


RESULTS  AT  PRESENT  BEING  OBTAINED     13 

AVERAGE  OF  250  TYPICAL  BOILER  PLANTS. 

A.  Working  Day's  Test  ;— 

Type  of  boiler      .         .                 .        .        .  "Lancashire" 
Number  of  boilers         .         .         .         .         .         .4 

Grate  area 152-6  sq.  ft. 

Duration  of  test    .         .         .         .         ...  9-43  hours 

Amount  of  fuel  used 30,13172  Ibs. 

Analysis  of  fuel  used  : — 

British  thermal  units     .....  11,822 

Ash 11-5  per  cent. 

Fuel  burnt  per  boiler  per  hour      ....  798-8  Ibs. 

„        „       ,,    square  foot  of  grate  area  per  hour  20*9      „ 

Water  evaporated 197.776  Ibs. 

,,              ,,          per  boiler  per  hour  .         .         .  5243         ,, 
,,              ,,            „   square  foot  grate  area  per 

hour       ....  137-4  Ibs. 

„   lb.  fuel       ....  6-56     ,, 
Equivalent  evaporation  from  and  at  212°  F.  per 

lb.  fuel 7-46  Ibs. 

Equivalent  evaporation  from  and  at  212°  F.  per 

1,000,000  British  Thermal  Units       .         .         .  631-0  Ibs. 

Temperature  of  feed-water  before  economiser      .  116°  F. 

after           „                 .  193°   „ 

Percentage  of  fuel  bill  saved  by            ,,                 .  7*1  per  cent. 

Draught  in  side  flue 0-40  in.  W.G. 

,,         ,,  main  flue  at  exit  of  economisers  or 

chimney  base        ....  o'8o   ,,       ,, 

Temperature  of  flue  gases  before  economisers     .  598°  F. 

„     „       ,,      after             „                .  478°  „ 
Percentage  of  CO2  in  flue  gases  from  side  flue  of 

boilers  by  means  of  combustion  recorder  .         .  7-6  per  cent. 
Steam  pressure  : — 

Lbs.  per  square  inch  (gauge)         .         .        .  89 

,,       „        ,,         ,,     (absolute)    .        .         .  104 
Temperature  of  saturation  of  steam      .         .        .  330-5°  F. 
,,            ,,  superheated  steam       ,        .        .  346*5°  ,, 
Steam  or  power  used  as  auxiliary  to  the  produc- 
tion of  steam     .         ...         .         .         .  2 -4  per  cent. 

Thermal  efficiency  : — 

(a)  Net   working  efficiency  complete,  after 

deducting  2-4  per  cent,  steam  or  power 
used  as  auxiliary  to  the   production  of 

steam 60-09  per  cent. 

(b)  Boilers  only '  .  56*71    ,,      ,, 

(c)  Economisers  only 4-35    ,,      ,, 

(d)  Superheaters     ,,                .         .        ...  0-51    ,,      ,, 

B.  Long  Check  Test  (one  week  of  7  days) : — 

Duration      .         .         .         .         ...        .  167-5  hours 

Amount  of  fuel  used     .         .         .         .      '  «-        .  128-25  tons 

Water  evaporated         ......  184,435-0  galls. 

,,              ,,          per  lb.  coal       .        .        .         .  6-42  Ibs. 

Taking    separate    industries,    I    gave    in    "Engineering" 

(25th  July  and  1st  August,  1919,  "Exact  Data  on  the  Run- 
ning of  Steam  Boiler  Plants,  No.   2.     The  Performance   of 


BOILER  PLANT  TESTING 


Colliery  Steam  Boiler  Plants")  the  detailed  figures  for  the 
tests  of  100  different  colliery  boiler  plants,  representing  570 
boilers  with  an  annual  coal  bill  of  1,250,000  tons.  These 
colliery  plants  were  situated  as  follows : — 


Lancashire  .         .     '    .         .     * 

Derbyshire  . 

Gloucestershire    . 

Notts  .... 

Shropshire  . 

Scotland 

South  Wales 

Staffs  .... 

Yorkshire     . 

Warwickshire 


14 
8 

i 

7 
i 


26 


The  true  average    figures    for  these  100  tests  are  given 
below  : — 

A,  Working  Day's  Test  :— 

Duration  of  test g  68  hrs. 

Type  of  boiler .  Chiefly  "  Lane." 

Number  of  boilers Average  5*7 

Grate  area 217*6  sq.  ft. 

Number  of  tubes  in  economiser           ....  Average  50. 
Analysis  of  coal  used : — 

B.Th.U 10,500 

Ash 15-5  per  cent. 

Amount  of  coal  burnt           .  .      .       ,.*         ,/..*-    .         .  39,815  Ibs. 

Coal  burnt  per  boiler  per  hour     .         .          ~~~    .         .  721-5      ,, 

,,        ,,       ,,    sq.  ft.  grate  area  per  hour            .         .  18-9      ,, 
Draught  :— 

Chimney  base       '.."••         .         .         .         .         .  0-95  ins.  W.G. 

Side  flues .  o'6o    ,,         ,, 

Temperature  of  flue  gases  : — 

Before  economiser    .        ...        . '       .         .  690°  F. 

After              „ f  .  660°  „ 

Percentage  of  CO2        .         .        *        •        .                 *  7*5  per  cent. 

Total  water  evaporated 21,693  gals. 

Water  evaporated  per  boiler  per  hour           ..  "     .         .  393  gals. 
Temperature  of  feed-water  : — 

Before  economiser .  137°  F. 

After            „            . 154°  „ 

Per  cent,  saving  due  to  economisers    .         .         .  i'6  per  cent. 

Steam  pressure  gauge 86  Ibs. 

Temperature  of  saturated  steam 328 '4°  F. 

„           ,,  superheated  steam       .         .         .         .  350-0°  ,, 
Steam  or  power  used  as  auxiliary  to  the  production 

of  steam ,         ,  i -8  per  cent. 

Lbs.  water  per  Ib.  coal 5-44  Ibs. 

„        ,,     from  and  at  212°  F.  per  Ib.  coal          .         .  6*07    ,, 

„         „       ,,     „     „      „     „    1,000,000  B.Th.U.  578-1    „ 
Efficiency : — 

(a)  Net  working 55'52  per  cent. 

(b)  Boilers  only 55*°2    ,,       „ 

(c)  Economisers  only 0-90    „       ,, 

(d)  Superheaters    ,, 0-62    ,,       ,, 


RESULTS  AT  PRESENT  BEING  OBTAINED     15 

B.  Long  Check  Test  (one  week  of  7  days)  : — 

Duration  of  test 168-00  hrs. 

Amount  of  coal  burnt .         .       235-2  tons 

,,        „  water  evaporated  ......  273,990  gals. 

Water  evaporated  per  Ib.  of  coal     .         .    ,    .         .        .         5'ig  Ibs. 
Approximate  annual  coal  bill  .        .         .         .         .       11,800  tons 

The  figures  can  be  divided  as  follows : — 

Net  Working  Efficiency.  No  of 

(Boilers,  Economises  and  Superheaters.)  Plants. 

1.  80  per  cent,  and  over o 

2.  75    „,,.»„  •         .         .        .         .  o 

3.  70   „       „       ..       ..  •         •         •         •         •  i 
4-  65    „       „       „       „  .....  4 

5.  60   „       „       „        „  .....  9 

6.  55   »»       .*       »       > 29 

7.  50    „,,,,,, 

8.  Below  50  per  cent.  .....          35 

Total         ....         100 

The  average  net  working  efficiency  of  55*52  per  cent  is  the 
lowest  of  any  industry  in  the  country,  although  not  so  low  in 
comparison  as  is  generally  supposed.  One  reason  why  the 
efficiency  of  colliery  boiler  plants  in  general  is  lower  than  the 
average,  is  that  there  is  still  at  work  a  number  of  the  grossly 
inefficient  "egg-ended"  boilers.  I  will  deal  later  with  the 
efficiency  of  different  boilers,  but  out  of  the  570  boilers  in 
these  100  colliery  tests,  37  boilers  were  of  the  "egg-ended" 
variety,  500  being  "Lancashire,"  31  " water-tube "  and  2 
special  boilers.  The  second  reason  is  that  coal  at  the  colliery, 
until  a  few  years  ago,  was  so  cheap  as  hardly  to  be  worth 
saving,  and  consequently  the  boiler  plant  was  regarded  as  even 
of  less  importance  than  usual,  whilst  also  to  some  extent 
inferior  coal  is  used. 

Also  in  the  "Chemical  Trade  Journal"  of  August  and 
September,  1920  ("Coal  Saving  in  the  Chemical  Industry"), 
I  published  the  detailed  figures  for  the  tests  of  sixty  different 
chemical  works'  boiler  plants,  representing  236  boilers  with 
an  annual  coal  bill  of  620,000  tons  per  annum.  The  true 
average  figures  for  these  sixty  tests  are  as  follows  : — 


16  BOILER  PLANT  TESTING 

A.  Working  Day's  Test : — 

Duration  of  test 9-2  hrs. 

Type  of  boiler Chiefly  "  Lane." 

Number  of  boilers Average  3*9 

Grate  area 156*5  sq.  ft. 

Number  of  tubes  in  economiser Average  300 

Analysis  of  coal  used  :-^- 

B.Th.U.    .        .        .      *  .         .    f* .         .        .        .  11,350 

Ash .         .         .12  per  cent. 

Amount  of  coal  burnt 38,025  Ibs. 

Coal  burnt  per  boiler  per  hour 1059-8   ,, 

„        „       „    sq.  ft.  grate  area  per  hour     .         .        .  26-6   „ 
Draught : — 

Chimney  base 070  in.  W.G. 

Side  flues 0-38    „       „ 

Temperature  of  flue  gases  :    - 

Before  economiser 650°  F. 

After            „             450°  „ 

Percentage  of  CO2 8*0  per  cent. 

Total  water  evaporated 23>358  gals. 

Water  evaporated  per  boiler  per  hour  ....  651     ,, 
Temperature  of  feed- water  : — 

Before  economiser 103°  F. 

After            „              .......  215°  „ 

Per  cent,  saving  due  to  economisers     .         .         .  10-1  per  cent. 

Steam  pressure  (gauge) 102  Ibs. 

Temperature  of  saturated  steam  .        .       . .       . .         .  339'2°  F. 

„            „  superheated  steam       ....  384-2°  „ 

Steam  or  power  used  as  auxiliary  to  the  production  of 

steam 6-1  per  cent. 

Lbs.  water  per  Ib.  coal 6-1  Ibs. 

,,         ,,     from  and  at  212°  F.  per  Ib.  coal  .         .         .  7-0   ,, 

,,         ,,         ,,         „         „     „     ,,    1,000,000   B.Th.U.  616-7   ,, 
Efficiency : — 

(a)  Net  working 57-9  per  cent. 

(b)  Boilers  only 54-2    „      ., 

(c)  Economisers  only         .         .         .         ...  6'i    ,,      ,, 

(d)  Superheaters    „           .        .         .        .        '.        .  1-3    „      ,, 

B.  Long  Check  Test  (one  week  of  7  days) : — 

Duration  of  test  (hours) ^4-5 

Amount  of  coal  burnt  (tons)  .         .         .         .         .  145*62 

Amount  of  water  evaporated  (gallons) ....  18918-95 

Water  evaporated  per  Ib.  coal 5-89 

Approximate  annual  coal  bill 10,596  tons 

These   figures  for  the  chemical  industry  can  be  divided 
as  follows  : — 

Net  Working  Efficiency.  No.  of 

(Boilers,  Economisers,  and  Superheaters).  Plants. 

1.  80  per  cent,  and  over o 

2.  75    „       ,,       „       „ 4 

3-  70    „       „       „       „ 3 

4-  65    „       „       „       „ 12 

5-  60    „       „  9 

6.  55    „       „       „       „ 13 

7-  50    „       „       „       „ 9 

8.  Below  50  per  cent 10 

Total  .     60 


RESULTS  AT  PRESENT  BEING  OBTAINED      17 

Taking  again  another  group  of  allied  industries,  that  of 
dyeing,  bleaching,  calico-printing,  finishing,  and  dyeing  and 
cleaning,  in  the  "  Textile  Manufacturer"  of  August  to  March, 

1921  ("  Coal  Saving  by  Modern  Methods  of  Steam  Genera- 
tion "),  I  give  the  detailed  results  of  sixty-five  boiler  plants  in 
these  industries,  representing  217  boilers  with  an  annual  coal 
bill  of  275,637  tons  per  annum.  The  true  average  figures  for 
these  sixty-five  tests  are  as  follows  : — 

A.  Working  Day's  Test : — 

Duration  of  test  ....         ...  8*30  hrs. 

Type  of  boiler Mostly  "  Lane." 

Number  of  boilers       ......  Average  3*3 

Grate  area 118-60  sq.  ft. 

Number  of  tubes  in  economiser  .         .         .  Not  stated 

Analysis  of  coal  used  : — 

B.Th.U. 11,950 

Ash 10-5  per  cent. 

Amount  of  coal  burnt 20,776  Ibs. 

Coal  burnt  per  boiler  per  hour    ....  758-5     ,, 

„       „       ,,     sq.  ft.  grate  area  per  hour  .         .  21*17     ,, 
Draught : — 

Chimney  base          .         .         .         .         .         .  0*83  in.  W.G. 

Side  flues 039  ,,          „ 

Temperature  of  flue  gases  before  economiser      .  610°  F. 

„         „     ,,        „     after  „  .  460°  „ 

Percentage  of  C(  2 7-8  per  cent. 

Total  water  evaporated 13,829-9  gals. 

Water  evaporated  per  boiler  per  hour          .         .  504-8          ,, 
Temperature  of  feed-water  : — 

Before  economiser  ......  112-5°  F- 

After  „ 202-5°  ,, 

Percentage  saving  due  to  economisers        .         .  8-3  per  cent. 

Steam  pressure  (gauge)       .         .         ...  70  Ibs. 

Temperature  of  saturating  steam        .         .         .  316-5°  F. 

,,  ,,  superheated  steam     .         .         .  355-0°  „ 

Steam  or  power  used  auxiliary  to  the  production 

of  steam 2*0  per  cent. 

Lbs.  water  per  Ib.  coal       .....  6-65  Ibs. 

,,         ,,       from    and    at    212°    per    1,000,000 

B.Th.U.       .         .         .         .         .  7-60    „ 

Efficiency : — 

(a)  Networking 61-41  per  cent. 

(b)  Boilers  only 56-33        ,, 

(c)  Economisers  only       .         .         .         .         .  5*15          ,, 

(d)  Superheaters     „        .         .         .        ."  '   »  n8         „ 

B.  Long  Check  Test  (one  week  of  7  days)  : — 

Duration  of  test 163-93  hrs. 

Amount  of  coal  burnt 83-82  tons 

,,       ,,  water  evaporated      ....  167,717  gals. 

Water  evaporated  per  Ib.  coal    ....  6-5  Ibs. 

Approximate  annual  coal  bill      ....  4240  tons 


i8  BOILER  PLANT  TESTING 

The  figures  for  the  dyeing,  bleaching,  calico-printing, 
finishing,  and  dyeing  and  cleaning  industries  can  be  divided 
as  follows : — 

Net  Working  Efficiency.  No.  of 

(Boilers,  Economisers  and  Superheaters.)  Plants. 

1.  80  per  cent,  and  over i 

2.  75   „       „       „    "'-„'  .     .        >       ....  o 

3-  7<>   ,,       „„„....,...  4 

4-  65   M«        „       „         .         •         .         .         .         •  12 

5-  GO   „       „                „         ...         .         1         .  14 
6.  55    ,,       ,.        „       ,,         •         -     ~  .         .         .         .  12 
7-  5°    it       ii        ii       n         «         •         •         .         .  It  ,.  16 
8.  Below  50  per  cent.          .        ....        .        .  ••  6 

Total      .    .      •  .        .        65^ 

Finally,  I  gave  in  the  Annual  Number  (1921)  of  the 
"  Papermaker "  (March,  1922),  the  figures  for  the  paper- 
making  industry  ("  Coal  Saving  in  the  Papermaking  Industry 
by  the  Scientific  Control  of  Steam  Boiler  Plants"),  represent- 
ing forty  boiler  plants  with  1 1 2  boilers  and  an  annual  coal 
bill  of  291,145  tons  per  annum.  The  true  average  figures  for 
these  forty  tests  are  as  follows  : — 

A.  Working  Day's  Test :— 

Duration  of  test .  11*12  hrs. 

Type  of  boiler       .         .         .....         .         .  Mostly  "  Lane." 

Number  of  boilers         .         .         *.      .     '   .        .  Average  2-8 

Grate  area    .         .         .               „        .        .         »        .  102-87  sq.  ft. 

Number  of  tubes  in  economiser    .         ;         .         .         .  216 
Analysis  of  coal  used  : — 

B.Th.U .        .        .  n,53o 

Ash .         .  12*75  Per  cent. 

Amount  of  coal  used 236,005  Ibs. 

Coal  burnt  per  boiler  per  hour 757'9    ,, 

,,        ,,       ,,    sq.  ft.  grate  area  per  hour     .         .         .  20-6    ,, 
Draught : — 

Chimney  base -    .         .         .  0*85  in.  W.G. 

Side  flues .         .         .       ..~       .        ,~       .        .         .  0-45  ,,       „ 
Temperature  of  flue  gases :  — 

Before  econcmiser    .        .         ....        .  600°  F. 

After             „              ......         .         .  414°  F. 

Percentage  of  CO2        .         .         ,       ..         ...  8'o  per  cent. 

Total  water  evaporated        .        . '       .        .         .         .  16,873-4  gals. 

Water  evaporated  per  boiler  per  hour  .        ,         ,        .  54I-9     ,, 
Temperature  of  feed-water  : — 

Before  economiser    .       »;        .        .     -    .        ..      .  143°  F. 

After            „              .        .        *  -     ".        »        .        .  270°  „ 

Percentage  saving  due  to  economiser  .         .""j      .        .  11*9  per  cent. 

Steam  pressure  (gauge)         .       v        .        !,_       .        .  104  Ibs. 

Temperature  of  saturated  steam  .         .         .      „;  ,       _ .  340*6°  F. 

„             ,,  superheated  steam       .         .         .  360-0°  „ 

Steam  or  power  used  auxiliary  to  production  of  steam  .  3-75  per  cent. 

Lbs.  water  per  Ib.  coal          .        .         .         ...  7-15  Ibs. 

,,         ,,     from  and  at  212°  F.  per  Ib.  coal           .         .  7-95    ,, 

„      „     „    1,000,000  B.Th.U.  689-3      „ 


RESULTS  AT  PRESENT  BEING  OBTAINED     19 

Efficiency  :— 

(a)  Net  working        .  .  .  ...  .  65-07  per  cent. 

(b)  Boilers  only         .  .  .  .         .         .  .  58-91    „      ,, 

(c)  Economisers  only  .  .  <         .         .  .       S-oi    ,,      ,, 

(d)  Superheaters    „  .  .  .        .         .  .       0-69    ,,      „ 

B.  Long  Check  Test  :— 

Duration  of  test .         .          158-8  hrs. 

Amount  of  coal  burnt 125-61  tons 

„         „  water  evaporated 189,124  gals. 

Water  evaporated  per  Ib.  coal       .         .         .         .         .  672  Ibs. 

Approximate  annual  coal  bill        .....         7278  tons 

The  figures  for  the  papermaking  industry  can  be  divided 
as  follows : — 

Net  Working  Efficiency.  No.  of 

(Boilers,  Economisers  and  Superheaters.)  Plants. 

1.  80  per  cent,  and  over o 

2.  75    „       „  i 


3-  70 

4-  65 
5.  60 


i 
6 

7 

10 

8 


6.  55 
7-  50 
8.  Below  50  per  cent.  ......  7 

Total  •   .        .         .        4p_ 

I  am  also  tabulating  similar  figures  for  various  other  in- 
dustries, particularly  cotton  and  woollen  manufacture,  and  the 
general  results  are  almost  identical  with  the  four  industries 
already  given. 

The  striking  fact,  as  will  be  seen,  is  that,  in  averages,  in- 
dividual boiler  plants  are  working  at  all  kinds  of  efficiencies, 
actually  from  32  to  82  per  cent,  whilst  the  average  for  all  the 
400  boiler  plants  is  58  per  cent,  and  the  average  for  in- 
dividual industries  may  vary  from  55  to  65  per  cent  The 
results  being  obtained  in  general  can,  I  think,  be  conveniently 
expressed  by  a  series  of  tables  which  I  gave  in  "  Engineering," 
loth  to  1 7th  December,  1920  ("Exact  Data  on  the  Perform- 
ance of  Steam  Boiler  Plants,  No.  4.  Average  Figures  for  the 
Performance  of  Some  Different  Types  of  Steam  Boiler  Plant "). 

In  these  tables  I  have  given  for  the  various  types  of  boiler 
in  use,  first  of  all — as  much  the  most  important — the  figures 
being  obtained  to-day  under  average  conditions  without  any 
proper  methods  of  testing  and  control,  applying  to  at  least 


20  BOILER  PLANT  TESTING 

85  per  cent,  of  the  boiler  plants  of  the  country.  I  have  also 
given  in  the  case  of  "  Lancashire  "  and  "  Water-tube  "  boilers, 
corresponding  figures  for  plants  run  on  the  most  modern 
lines,  which  apply  only  to  probably  about  5  per  cent,  of  boiler 
plants,  and  at  the  same  time  I  have  given  figures  for  very  bad 
plants,  probably  typical  of  about  10  per  cent,  of  the  plants  of 
the  country. 

In  order  to  present  comparative  figures,  the  coal  used 
throughout  has  been  calculated  as  12,000  B.Th.U.  per  pound 
gross,  and  10-5  per  cent,  ash,  which  represents  roughly  the 
average  quality,  or  slightly  above  the  average,  used  through- 
out the  country. 

Also,  for  the  purpose  of  comparison,  I  have  taken  an 
average  price  of  403.  per  ton,  and  calculated  the  day's  test  and 
the  week's  test  in  pence  per  1000  gallons,  together  with  a  coal 
bill  for  a  standard  evaporation  of  20,000,000  gallons  of  water. 

Further,  in  taking  the  temperature  of  the  feed-water  (as 
going  into  the  plant)  an  average  figure  of  110°  E.  has  been 
taken  throughout,  because  this  is  about  the  usual  figure,  being 
the  ordinary  "  hot  well  "  temperature.  In  studying  the  figures, 
therefore,  if  the  temperature  of  the  inlet  water  of  a  particular 
plant  is  different,  every  11°  F.  can  be  taken  as  equivalent  to 
I  per  cent,  of  the  coal  consumption,  higher  or  lower.  Thus, 
if  the  feed-water  be  about,  say,  99°  F.  then  the  coal  consump- 
tion figures  will  be  increased  about  I  per  cent. 

LANCASHIRE  BOILER  PLANT. 

The  adjoining  table  gives  what  I  consider  to  be  the 
average  figures  for  the  performance  of  the  "  Lancashire " 
boiler  complete  with  all  accessories,  calculated  in  terms  of 
standard  30  x  8  ft.  boilers  with  average  grates  6  x  3  ft.  2  in. 

A  plant  of  four  boilers  is  given  because  this  is  about  the 
average  size  and,  of  course,  for  a  different  number  of  boilers 
the  corresponding  figures  can  easily  be  calculated. 

As  regards  the  method  of  firing,  hand  and  mechanical 
firing  are  averaged  together,  as  there  is,  in  my  opinion,  little 


RESULTS  AT  PRESENT  BEING  OBTAINED     21 


LANCASHIRE  BOILER  PLANT. 


Bad  Plant 
Representing, 
say,  10  Per 
Cent,  of 
Boiler  Plants 
at  Work  in 
Great  Britain. 

Ordinary  Aver- 
age Plant  as 
being  Generally 
Woiked  To-day, 
Representing 
85  Per  Cent,  of 
Plants  at  Work 
in  Great  Britain 

Most  Efficient  Plant 
Working  under 
Modern  Scientific 
Supervision  or  under 
Test  Conditions, 
Representing  only 
about  5  Per  Cent,  of 
Plants  at  Work  in 
G  eat  Britain. 

A.  WORKING-DAY  TEST. 
i.  Number  of  boilers  working     . 
2.  Grate  area  (total)     

4 
151-96  sq.  ft. 

4 
151*96  sq.  ft. 

4 
151-96  sq.  ft. 

4.  Price  of  coal  used  (per  ton  delivered)    . 
5.  Amount  of  coal  used       
6.  Analysis  of  coal—  B.Th.U  

40s. 
36,249  Ibs. 

I2.0CO 

403. 
41,504  Ibs. 
12,000 

4os. 
50,870  Ibs. 
12,000 

8.  Coal  burned  per  boiler  per  hour    . 
9.  Coal  burned  per  sq.  ft.  grate  area  per  hour  . 
10.  Water  evaporated,  Ibs  
1  1.  Water  evaporated  per  boiler  per  hour   . 
12.  Water  evaporated  per  sq.  ft.  grate  area  per 
hour   
13.  Water  evaporated  per  Ib.  of  coal   . 
14.  Equivalent  evaporation  from  and  at  212°  F. 

755*2  Ibs. 
19-8  Ibs. 
204,000  Ibs. 
4250  Ibs. 

in'3  Ibs. 
5-62  Ibs. 

6*42  Ibs 

864-7  Ibs. 
22*7  Ibs. 
276,000  Ibs 
575°  Ibs. 

151-3  Ibs. 
6-65  Ibs. 

7-62  Ibs. 

1059-8  Ibs. 
27  9  Ibs. 
408,000  Ibs. 
8500  Ibs. 

2237  Ibs. 
8-02  Ibs. 

9*28  Ibs 

15.  Equivalent  evaporation  from  and  at  212°  F. 
per  1,000,000  B.Th.U  
16.  Temperature  of   fe;d-water    before  econo- 

535'i  Ibs. 
110°  F. 

635-0  Ibs. 
110°  F 

856-7  Ibs 
110°  F 

17.  Temperature  of  feed-water  after  economisers 
1  8.  Percentage  of  coal  bill  saved  by  economisers 
19.  Draught  in  back  flues  of  boilers     .        .        . 
20.  Draught  in  chimney  base        .        . 
21.  Temperature  of  flue  gases  before  economisers 
22.  Number  of  economiser  tubes 
23.  Temperature  of  flue  gases  after  economisers 
24.  Analysis  of  boiler  feed-water  — 
Degrees  permanent  

No  economiser 
Nil 
0-40  in.  W.G. 
0*50  in.  W.G. 
500°  F. 
No  economiser 
500°  F. 

12° 
cO 

230°  F. 
i  I'D  per  cent. 
0-35  in.  W.G. 
075  in.  W.G. 
600°  F. 
About  320  tubes 
450°  F. 

9° 

335°  F. 
2O'4  per  cent. 
065  in.  W.G. 
2-00  in.  W.G. 
650°  F. 
About  500  tubes 
310°  F. 

5° 

0° 

25.  Percentage  COg   in   flue   gases   (continuous 
record  on  combustion  recorder)       . 
26.  Steam  pressure  (average)  —  (a)  Gauge    . 
27.  Steam  pressure  (average)  —  (b)  Absolute 
28.  Temperature  of  saturation  of  steam 
29.  Temperature  of  superheated  steam 
30.  Steam  or  power  used  as  auxiliary  to  produc- 

5-0  per  cent. 
60  Ibs. 
75  Ibs. 
307*4°  F. 
None 

7-5  per  cent. 
75  Ibs. 
90  Ibs.      - 
320-3°  F. 
None 

i2'o  per  cent. 
159  Ibs. 
174  Ibs. 
37  'c°  F. 
540°  F. 

Thermal  efficiency  of  plant  — 
31.      (a)  Net  working  efficiency  of  plant  complete 
32.      (b)  Boilers  only    ...... 

49-2  per  cent. 
51*8  per  cent 

60  -o  per  cent. 
54-7  per  cent. 

79-o  per  cent. 
59'5  Per  cent. 

Nil 

34.      (d)  Superheaters  only          .... 
35.  Cost  in  coal  to  evaporate  1000  gals,  of  water 

B.  LONG  CHECK  TEST  (ONE  WEEK). 
(Say  Two  Shifts  per  24  Hours.) 
36.  Duration  ........ 
37.  Price  of  coal  used  (per  ton  delivered)    . 
38.  Amount  of  coal  used        ...                 . 

Nil 
38o-8d. 

i68'o  hours 
403. 

Nil 
332'6d. 

i68'o  hours 
4os. 

6  2  per  cent. 
266  -gd. 

168-0  hours 

403. 

39.  Water  evaporated   
40.  Water  evaporated  per  Ib.  of  coal   . 
41.  Cost  in  coal  to  evaporate  1000  gals  of  water 
42.  Coal  bill  for  20,000,000  gals,  evaporated  per 

149  1  80  gals. 
5'55  Ibs. 
386-id. 

ft.2  166 

203  840  gals. 
6*50  Ibs. 
32g-6d. 

404,430  gals. 
7-85  Ibs. 
273  -od. 

/22  74.8 

22  BOILER  PLANT  TESTING 

difference  in  efficiency  between  the  two  methods.     I  propose 
to  deal  with  this  question  more  in  detail  on  page  42. 
With  regard  to  the  following  points  : — 

1.  Coal   Burnt  per  Boiler  per   Hour.— Calculated   as 
12,000  B.Th.U.  coal  the  average-figures  can  be  taken  as  about 
865   Ibs.   per    30    x  8    ft.  boiler  per  hour,  corresponding   to 
about  22|  Ibs.  per  square  foot  grate  area  per  hour.     A  very 
bad  plant  will,  as  seen,  burn  less  than  this,  whereas  a  plant  on 
modern  lines  would  give  about  20  per  cent,  more  duty  in  this 
respect. 

2.  Water  Evaporated  per  Boiler  per  Hour — Calculated 
at  110°  F.  inlet  temperature,  the  average  is  just  below  6000 
Ibs.   per  30   x  8  ft.  boiler.      This  is  considerably  less  than  is 
generally  supposed,  and  most  steam  users  imagine  that  some- 
thing like  8500  Ibs.  is  the  figure  being  obtained  ;  this,  however, 
does  not  apply  to  more  than  about  5  per  cent,  of  the  plants  of 
the  country.      In  general,  the  boiler  plants  of  Great  Britain 
are  working  at  nothing  like  their  proper  output,  which  is  in- 
teresting in  view  of  the  fact  that  hundreds  of  works  are  at  the 
same  time  in  continual  trouble  due  to  shortage  of  steam. 

3.  Water  Evaporated  per  Pound  of  Coal.— This,  of 
course,  depends   on  the   heating  value   of  the  coal  and  the 
temperature  of  the  feed-water,  but  taking  as  usual  the  averages 
of  12,000  B.Th.U.  and   110°  F.   the  figure  is  6-65  Ibs.  corre- 
sponding to  7-62  Ibs.  from  and  at  212°  F.     For  all  practical 
purposes,  the  figure  can  be  tak^n  as  6*5  Ibs.  corresponding  to 
7*5  Ibs.  from  and  at  2I2°F.      For  bad  plants  and  especially 
those    without    economisers,    the    figures    are,    say,    5*5    and 
6-5  Ibs.   respectively.      Figures  like  9  to  10  Ibs.  of  water  from 
and  at  212°  F.   per  Ib.  of  coal,  which  are  popularly  imagined 
to  apply  to  most  boiler  plants,  only  apply  to  about   5    Per 
cent,  of  the  plants  of  the  country. 

4.  Draught. — The  draught  of  the  average  boiler  plant  is 
obtained  by  means  of  a  chimney  (natural  draught)  giving  a 
draught  in  the  base  of  about  075   in.  suction  water  gauge, 
which,  with  the  average  flues  and  economisers  corresponds  to 


RESULTS  AT  PRESENT  BEING  OBTAINED     23 

about  0*35  in.  water  gauge  in  the  side  flues.  The  height  of 
a  chimney  corresponding  to  these  figures  is,  roughly,  say, 
125  to  150  ft.  with  average  flues.  In  the  case  of  bad  plant, 
a  short  chimney,  say,  90  to  120  ft.,  and  cramped  and  de- 
fective flues,  the  draught  corresponds  to  only  about  0-5  in. 
water  gauge  in  the  chimney  base.  Without  economisers  this 
is  equal  to,  say,  0*4  in.  in  the  side  flues.  If  economisers  are 
installed  under  such  conditions,  say,  an  average  of  320  tubes 
for  4  boilers,  there  is  a  very  serious  reduction  in  the  draught, 
and  in  the  side  flues  the  figure  would  then  only  be  about 
0*20  in.  water  gauge.  On  a  good  plant,  using  mechanical- 
induced  draught,  the  figure  averages  about  2  ins.  water  gauge 
in  the  flue  near  the  fan  inlet,  and  0^65  in.  water  gauge  in  the 
side  flues,  much  thicker  fires  being  used. 

5.  Temperature  of  Flue  Gases. — The  gases  leaving  the 
boilers  average  about  600°  F.  with  coal  of  12,000    B.Th.U. 
On  a  bad  plant  with  a  poor  draught  and  leaky  brickwork,  the 
figure  is  only  about  500°  F.,  chiefly  because  of  cold  air  leakages. 
In  a  most  efficient  plant  the  figure  goes  up  to,  say,  65o°F., 
because  of  tight  brickwork  and  good  fires  with  a  minimum  of 
excess  air.     With  too  much  draught  or  "short  circuiting"  of 
the  gases   in  the  boiler  seatings,    however,  the  temperature 
may  go  as  high  as  800°  F.  leaving  the  boiler. 

6.  Quality  of  Feed- Water. — The  average  figures  for  feed- 
water  are   about    11°   total   hardness,  that    is   1 1   grains    per 
gallon,  and  this  means  a  considerable  deposit  of  scale  with  a 
corresponding  loss  in  efficiency.      It  is  difficult  to  express  the 
advantage  of  softening  the    feed  water  in  figures  of  annual 
saving  in  the  coal  bill,  but  a  good  plant  should  not  have  have 
a  hardness  of  over  5°  to  6°,  and  a  softening  plant  is  necessary 
in  average  cases  to  obtain  such  figures.     A  typical  average 
bad  plant  has,    say,   17    grains  per  gallon,  which  of  course 
means  serious  scale  troubles. 

7.  Percentage  of  CO2. — The  average  plant  is  only  giving, 
say,  7'5   per  cent.  CO2  in  the  side  flues,  because  of  medium 
firing  and    leaky  brickwork,  whilst  a  very  efficient  plant    is 


24  BOILER  PLANT  TESTING 

about  12  per  cent.  It  must  be  remembered,  however,  that 
high  CO2  does  not  mean  efficiency  unless  at  the  same  time 
there  is  no  CO  (carbon  monoxide)  present,  and  the  figure  for 
CO2  is  apt,  therefore,  to  be  deceptive.  In  averages  the  figures 
for  CO  are,  say,  cri  to- 0*3 5  percent.,  and  in  good  cases  O'l 
to  O'2  per  cent.,  bad  cases  being  over  I  per  cent. 

8.  Economisers. — As  will  be  discussed  later,  the  average 
saving  in  practice  due  to  economisers  is  nothing  like  so  great 
as  commonly  imagined,  averaging  about   1 1   per  cent,  of  the 
coal  bill  instead  of  1 5  to  20  per  cent,  as  usually  stated  by 
economiser    makers.      For    the    "  Lancashire "    boiler    plant 
to-day   of  four   boilers,   30  x  8    ft.,    320   tubes,   9   ft.   tubes, 
may  be  regarded  as  representing  average  practice,  giving  1 1 
per  cent,  saving  in  the  coal  bill,  and  raising  the  feed-water 
from   110°  to  230°  F.     As  previously  stated,  in  calculating  the 
saving,  roughly  ii°F.   rise  in  the  feed-water  corresponds  to 
I    per   cent,    saving    in    the    coal    bill.     The    installation    of 
economisers  chokes  the  draught  in  the  case  of  chimney  draught, 
because  of  the  reduction  in  the  temperature  of  the  gases  at  the 
chimney  base.     Thus,  taking  a   typical  case  of    a    chimney 
170  ft.  high,  with  gases  600°  F.   in  the  base,  giving  1*14  in. 
W.G.  at  the  chimney  base,  if  economisers  are  installed  and 
the  flue  gases  reduced  in  temperature  to  35o°F.  the  draught 
would  then  only  be,  say,  0*70  in.  water  gauge.     In  a  plant 
run  on  the  most  up-to-date  lines  the  saving  can  average  1 8  to 
20  per  cent,  and  17^5  per  cent,  can  be  taken  as  a  fair  average 
figure  for  a  good  economiser  installation,  if  modern  scientific 
methods  of  control  are  adopted  throughout. 

9.  Superheaters. — Expressed    in  averages,  the   ordinary 
"  Lancashire"  boiler  plant  can  be  stated  to  be  working  without 
superheaters,  and  the  boiler  plants  of  Great  Britain  make  very 
little  use  of  superheating.     When  installed,  a  rough  calcula- 
tion is,  say,  0*05  per  cent,  saving  in  the  coal  bill  for  every  1°  F. 
rise  in  the  temperature  of  the  steam  above  saturation  point.     A 
plant  on  modern  lines  will  superheat  the  steam  to,  say,  170° 
to  200°  F.  above  saturation  point,  and   reduce  the  coal  bill 


RESULTS  AT  PRESENT  BEING  OBTAINED     25 

9  to  10  per  cent,  in  addition,  of  course,  to  the  extra  efficiency 
in  the  engine  or  turbine. 

10.  Steam  or  Power  Used  Auxiliary  to  the  Production 
of  Steam. — As  will  be  discussed  later  (p.  45),  the  amount 
of  steam  used  by  steam  jets  is  much  greater  than  is  commonly 
supposed.     The  average  figure  we  found  to  be  6 '6  per  cent, 
of  the  steam  production  of  the  plant,  being  the  same  for  both 
mechanical    stokers    and    hand-fired    steam-jet    furnaces,   the 
general  impression  being  that  it  is  only  about  I  to  2  per  cent. 
On  individual  plants  the  figure  may  be  anything  from  0*5  to 
20  per  cent,  and  more  detailed  figures  are  given  on  page  104. 
Mechanical  forced,  or  induced  draught  generally  takes  about 
2*5  per  cent,  of  the  production  at  full  output.     As  we  have  no 
proper  engineering  census,  it  is  difficult  to  give  average  figures 
for  auxiliary  steam  or  power  consumption,  because  it  is  not 
known  what  proportion  of   the  boiler  plants  of  the  country 
use  such    apparatus.     I  estimate    roughly  that  the  figure  is 
35  per  cent,  of  the  plants  of  Great  Britain,  and  2-5   per  cent, 
for  the  steam  consumption  for  auxiliary  power  for  the  whole 
of  the  plants  of  the  country  is    probably  not  far  wrong.      I 
have  taken  the  bad  plants  as   5   per  cent.,  and  2*5   percent, 
would  still  be  required  by  the  most  up-to-date  plant.      Natur- 
ally, in  calculating  the  net  working  efficiency  of  a  boiler  plant 
such  steam  has  to  be  deducted,  as  it  is  not  useful  steam,  a 
point  which  will  also  be  discussed  later. 

11.  Efficiency  of  Plant. — In  averages,  a    "Lancashire" 
boiler  plant  is  working  at,  say,  54-5   per  cent,  for  the  boilers 
only,  and  60  per  cent  for  the  whole  plant,  including  econo- 
misers  and  superheaters,  and  deducting  2 '5   per  cent,   for  the 
auxiliary  steam.     Bad  plants  may  be  about   50  per  cent,  net 
working  efficiency.      As  already  seen,  this  is  very  much  less 
than  is  commonly  supposed,  the  usual  empirical  figures  in 
general  use  corresponding  to  about  75  to  80  per  cent,  network- 
ing efficiency,  which  is  entirely  erroneous.     A  modern  plant 
will  give  about  60   per   cent,   efficiency  on   the  boiler  only, 
corresponding  to  about  79  per  cent   net  working  efficiency, 


26 


BOILER  PLANT  TESTING 


WATER-TUBE  BOILER  PLANT. 


-'  • 

Bad  Plant 
Representing, 
say.  10  Per 
Cent,  of 
Boiler  Plants 
at  Work  in 
Great  Britain. 

Ordinary  Aver- 
age Plant  as  be- 
ing Generally 
Worked  To-day, 
Representing 
85  Per  Cent,  of 
Plants  at  Work 
in  Great  Britain. 

Most  Efficient  Plant 
Working  under 
Modern  Scientific 
Supervision  or  under 
Test  Conditions, 
Representing  onlv 
about  5  Per  Cent,  of 
Plants  at  Work  in 
Great  Britain. 

A.  WORKING-DAY  TEST. 
i.  Number  of  boilers  working    .        .        .        .  , 
2.  Grate  area  (total)   
3.  Duration  of  test      .                 .                .        . 

560-0  sq.  ft. 
12  hours 

4 
560*0  sq.  ft. 
12  hours 

560-0  sq.  ft. 
12  hours 

4.  Price  of  coal  used  (per  ton  delivered)  . 
5.  Amount  of  coal  used              . 

4os. 
139,765  Ibs. 

403. 
141,040  Ibs. 

403. 
137,275  Ibs. 

6.  Analysis  of  coal—  B.Th.U  

7.  Analysis  of  coal  —  ash 

12,000 
10*5  per  cent. 

12,000 
io*5  per  cent. 

12,000 
io'5  per  cent. 

8.  Coal  burned  per  boiler  per  hour  . 
9.  Coal  burned  per  sq.  ft.  grate  area  per  hour 
10.  Water  evaporated,  Ibs.          .... 

2911-7  Ibs. 
20-8  Ibs. 
898,656  Ibs. 

2938-3  Ibs. 
20*9  Ibs. 
989,352  Ibs. 

2859-9  Ibs. 
20-4  Ibs. 
1,081,200  Ibs. 

ii.  Water  evaporated  per  boiler  per  hour 
12.  Water  evaporated  per  sq.  ft.  grate  area  per 
hour    
13.  Water  evaporated  per  Ib.  of  coal 
14.  Equivalent  evaporation  from  and  at  212°  F. 
per  Ib  of  coal 

i8,722'o  Ibs. 

1337  Ibs. 
6-43  Ibs. 

7-46  Ibs. 

20,6ii'o  Ibs. 

147-2  Ibs. 
7'oi  Ibs. 

8-12  Ibs. 

22,525-0  Ibs. 

160-9  Ibs. 
7-87  Ibs. 

9'  1  1   Ibs. 

15.  Equivalent  evaporation  from  and  at  212°  F. 
per  1,000,000  B.Th.U  
16.  Temperature   of  feed-water  before  econo- 

621  '6  Ibs. 
110°  F. 

676-6  Ibs. 
iio°F. 

759-2  Ibs. 
110°  F. 

17.  Temperature  of  feed-water  after  economisers 
18.  Percentage  of  coal  bill  saved  by  economisers 
19.  Draught  in  back  flues  of  boilers   . 
20.  Draught  in  chimney  base     .... 
21.  Temperature  of  flue  gases  before  economisers 
22.  Number  of  economiser  tubes 
23.  Temperature  of  flue  gases  after  economisers 
24.  Analysis  of  boiler  feed  water  — 
Degrees  permanent    
Degrees  temporary    
25.  Percentage  COz  in  flue  gases   (continuous 
record  on  combustion  recorder) 
26.  Steam  pressure  (average)  —  (a)  Gauge  . 
27.  Steam  pressure  (average)  —  (b)  Absolute 
28.  Temperature  of  saturation  of  steam     . 
29.  Temperature  of  superheated  steam 
30.  Steam  or  power  used  as  auxiliary  to  produc- 
tion of  steam      
Thermal  efficiency  of  plant  — 
31.      (a)  Net  working  efficiency  of  plant  complete 
32.      (b)  Boilers  only          . 

tf  o  economisers 
None 
070  in.  W.G. 
0*75  in.  W.G. 

575°  F. 
None 
575°  F. 

9° 

2° 

5-0  per  cent. 
150  Ibs. 
165  Ibs. 
365-9°  F. 
450-0°  F. 

2  '5  per  cent. 

61*0  per  cent. 
59*9  per  cent. 

195°  F. 
7-4  per  cent. 
0*35  in.  W.G. 
0*50  in.  W.G. 
475°  F. 
200 
325°  F. 

6° 

2° 

6'o  per  cent. 
155  Ibs. 
170  Ibs. 
368-3°  F. 
530-0°  F. 

2*0  per  cent. 

69-2  per  cent. 
60*3  per  cent. 

225°  F. 
io'  4  per  cent. 
0-30  in.  W.G. 
0-65  in.  W.G. 
450°  F. 
250 
300°  F. 

£ 

12-5  per  cent. 
160  Ibs. 
175  Ibs. 
370-5°  F. 
650-0°  F. 

1-5  per  cent. 

81  -9  per  cent. 
65*8  per  cent. 

33.      (c)  Economisers  only        .        .        .        » 
34.      (d)  Superheaters  only         .... 
35.  Cost  in  coal  to  evaporate  1000  gals,  of  water 

LONG  CHECK  TEST  (ONE  WEEK). 
(Say  Two  Shifts  per  24  Hours.) 
36.  Duration         ....... 

None 
2'6  per  cent. 
333'2d. 

168  hours 

4-9  per  cent. 
5-4  per  cent. 
305'3d. 

168  hours 

7-6  per  cent. 
9-7  per  cent. 
272'od. 

168  hours 

37.  Price  of  coal  used  (per  ton  delivered)    . 

4os. 
458*2  tons 

40s. 
452*0  tons 

403. 
467-5  tons 

39.  Water  evaporated  
40.  Water  evaporated  per  Ib.  of  coal 
41.  Cost  in  coal  to  evaporate  1000  gals,  of  water 
42.  Coal  bill  for  20,000,000  gals,  evaporated  per 
annum  (say  220  tons  of  coal  per  week) 

651,  740  gals. 
6-35  Ibs. 
337'4d. 

£28,120 

703,674  gals. 
6-95  Ibs. 
3o8-3d. 

£25,688 

815.769  gals. 
7-79  Ibs. 
275'od. 

£22,920 

RESULTS  AT  PRESENT  BEING  OBTAINED     27 

although  individual  "  Lancashire  "  boiler  plants  can  be  worked 
at  80  per  cent,  net  working  efficiency,  or  even  over.  This,  as 
seen,  includes  the  full  use  of  economisers  and  super-heaters, 
but  allowing  also  for  any  mechanical  draught  with  the  con- 
sequent 2-5  per  cent,  auxiliary  steam  required  to  drive  the  fan. 
These  figures  can,  in  general,  be  said  to  apply  to  all  large 
cylindrical  boilers  such  as  "Cornish  "and  "Marine"  boilers, 
and  the  various  adaptions  of  such  boilers  with  smaller 
tubes  used  in  conjunction  with  the  ordinary  standard  furnace 
tubes. 

WATER-TUBE  BOILER  PLANT. 

The  corresponding  figures  for  water-tube  boiler  plants  are 
given  on  the  adjoining  page,  calculated  for  standard  sized  water- 
tube  boilers  with  a  rated  evaporation  of  20,000  Ibs.  water  per 
hour  each,  say,  about  5250  sq.  ft.  of  heating  surface,  with  grates 
14x5  ft,  taking  as  a  typical  plant  five  or  six  such  boilers, 
four  working  at  a  time.  The  boilers  are  fired  by  mechanical 
stokers,  as  very  few  water-tube  boilers  are  hand-fired,  except 
small  boilers  of,  say,  10,000  Ibs.  hourly  evaporative  capacity. 
When  fitted  with  economisers,  each  boiler  has  its  own  separate 
set  of  economisers,  the  present  standard  practice.  The  water- 
tube  boiler  plant  may  be  said  to  be  the  typical  power  station 
plant,  and  is  also  installed  in  many  factories  where  high  steam 
pressure  is  required.  There  are,  of  course,  a  considerable 
number  of  different  makes  of  water-tube  boilers  on  the 
market,  some  of  which  give  more  efficient  results  than  others, 
but  I  have  endeavoured  to  give  average  figures  for  water- 
tube  boilers  generally. 

1.  Coal   Burnt  per    Boiler  per  Hour. — Calculated    as 
12,000    B.Th.U.   coal,  the    average    figures   can    be  taken  as 
about  28,000  Ibs.  (say   1-25  tons)  per  hour  (20,000  Ibs.  boiler 
as  already  stated',  corresponding  to  2O'5   Ibs.  per  sq.   ft.  grate 
area  per  hour.     The  rate  of  consumption  of  coal  on  the  average 
water-tube  boiler  is  roughly  about  the  same,  irrespective  of 
the  results  being  obtained. 

2.  Water  Evaporated  per  Boiler  per  Hour. — In  average 


28  BOILER  PLANT  TESTING 

plants  the  rated  evaporation  is  being  obtained,  namely  20,000 
Ibs.  per  hour,  and  on  very  efficient  plants  the  boiler  plant  is 
often  working  regularly  on  10  to  20  per  cent,  overload.  It 
is  only  on  very  bad  plants  that  the  nominal  evaporation  is  not 
being  obtained,  and  there  is  not  tfce  same  difference  in  evapora- 
tion between  different  water-tube  boiler  plants  as  there  is  with 
cylindrical  boiler  plants. 

3.  Water  Evaporated  per  Pound  of  Coal. — Calculated 
as  usual  on  12,000  B.Th.U.  coal  and  1 10°  F.   feed-water,  the 
average  figure  is  7  Ibs.  of  water  per  Ib.  of  coal,  corresponding 
to,  say,  8  Ibs.  of  water  from  and  at  212°  F.     On  bad  plants 
the  corresponding  figures  are  6*5  and  7-5   Ibs.     Here  again, 
the  average  figures  usually   taken,  such   as  10   Ibs.  of  water 
from  and  at  212°  F.  are  quite  erroneous,  and  only  apply  to  a 
few  plants. 

4.  Draught. — For   the  average    water-tube    boiler    plant 
the  standard  practice  is  to  use  mechanical   induced  or  forced 
draught,  or  a  combination  of  both,  with  a  short  steel  chimney, 
say,  60  to  100  ft.  high.      In  such  cases  the  draught  in  the  flue 
near  the  fan  inlet  is  only  about  0*5  in.  W.G.,  very  much  less  than 
induced  draught  for  cylindrical  boilers.     Roughly,  the  same 
figures  apply  to  a  most  modern  plant,  whilst  on  a  bad  plant  the 
draught  is  often  greater.       A    number    of  water-tube    boiler 
plants  are  worked  on  chimney  draught  only,  especially  small 
plants,  but  the  draught  obtained  in  practice  is  not  much  less, 
as  a  comparatively  high  chimney  is  then  generally  used. 

5.  Temperature  of  Flue  Gases. — In  the  average  water- 
tube  boiler  plant  the  gases  leave  the  boiler  at  about  470°  F., 
corresponding  to  about  325°  F.  in  the  chimney  base,  which  is 
very  much  less  than  in  the  case  of  cylindrical  boilers.     In  the 
case  of  a  bad  plant  the  gases  may  go  up  to,  say,  575°  F.  leav- 
ing the  boiler,  but  this  is  exceptional,  and  in  very  good  plants 
the  temperature  may  be  only  450°  F.    leaving  the  boiler,  and 
300°  F.  leaving  the  plant. 

6.  Quality  of  Feed- Water. — As  is  well  known,  scale  is 
much  more  serious  for  water-tube  boilers  than  for  cylindrical 


RESULTS  AT  PRESENT  BEING  OBTAINED     29 

boilers,  and  there  is  considerable  amount  of  trouble  with 
water-tube  boilers  because  of  scale.  In  average  cases,  the 
total  hardness  can  be  taken  as  8°,  and  in  bad  plants  ordinary 
feed-water  at,  say,  12°  hardness  is  used  regularly.  With  a 
modern  softening  plant,  which  reduces  the  make-up  water  to 
5°  to  6°  hardness,  and  the  use  of  engine  or  turbine  condensate, 
the  feed-water  should  not  average  more  than  3°  hardness. 

7.  Percentage  of  CO2. — The  average  percentage  of  CO2 
on  water-tube  boilers  with  mechanical  stokers  is  low,  averag- 
ing about  6  per  cent,  less  than  "Lancashire"  or  other  cylin- 
drical boilers.     In  the  chain  grate  type  of  stoker  the  fires  tend 
to  burn  thin  at  the  back  and  a  large  excess  of  air  passes,  so 
that  even  on  the  10  per  cent,  of  bad  plants  the  CO2  figure  is 
practically  as  good  as  the  85  per  cent,  average  plants.      On  the 
5  per  cent,  of  good  plants  this  error  is  avoided,  the  figure  being 
about  1 2 -5  per  cent. 

8.  Superheaters.— The  average  water-tube  boiler  installa- 
tion makes  much  better  use  of  superheaters  than  cylindrical 
boiler  installations,  and  the  average  figures  for  superheat  can 
be  taken  as,    say,    160°  to  200°    F.     Even  a  poor  plant  is 
almost  invariably  fitted  with  superheaters,  as  it  is  the  custom 
for  the  boiler  maker  to  include  superheaters  as  part  of  the 
installation  of  the  boiler.     In  a  very  modern  plant  very  high 
figures  are  obtained,  say  650°  F.  final  temperature,  correspond- 
ing to  about  250°  to  280°  superheat. 

9.  Economisers. — Economisers    give    less    saving    on    a 
water-tube  plant  than  with  cylindrical  boilers,  because  more 
heat  is    retained  by  a  water-tube   boiler,  leaving  less  to  be 
absorbed  by  the    economises     Thus,  in    average  cases,    the 
number  of  tubes  in  the  economiser  for  a  20,000  Ibs.  boiler  is 
200,  the  feed-water  being  heated  from  1 10°  F.  to,  say,  195°  F., 
saving  7-4  per  cent,  of  the  coal    bill.     On  a  poor  plant  no 
economisers  are  installed,  whilst  on  a  most  modern  plant  the 
saving    reaches,  say,    10-5   per    cent,    with    a  temperature  of 
225°  F.  in  the  feed- water  leaving  the  economiser. 

10.  Steam  or  Power  Used  Auxiliary  to  the  Production 


30  BOILER  PLANT  TESTING 

of  Steam. — It  is  almost  the  universal  custom,  as  already  stated, 
to  work  water-tube  boiler  plants  with  mechanical  forced  or 
induced  draught,  and  steam  jets  are  consequently  not  much 
used.  The  figures  for  auxiliary  steam  or  power  varies  from 
O'5  to  2-5  per  cent,  of  the  production  in  all  classes  of  plants. 

ii.  Efficiency  of  Plant. — On  the  average,  a  water-tube 
boiler  plant  is  working  at,  say  60  per  cent,  efficiency  for  the 
boilers  only,  and  69  per  cent,  for  the  whole  plant,  including 
economisers  and  superheaters,  and  deducting  the  power  used 
auxiliary  to  the  production  of  steam.  Bad  plants  may  only 
give  a  total  of  about  60  per  cent,  net  working  efficiency. 
These  figures,  again,  are  very  much  less  than  is  usually 
supposed.  It  is  a  common  belief  that,  generally  speaking,  a 
water-tube  boiler  plant  is  very  much  more  efficient  than  a 
cylindrical  boiler  plant,  and  that  more  or  less  all  water-tube 
boiler  plants  are  efficient.  This  idea  is  entirely  wrong. 
Figures  like  80  to  82  per  cent,  net  working  efficiency,  with 
65  per  cent,  due  to  the  boiler  only,  and  9  Ibs.  of  water  from 
and  at  212°  F.  per  Ib.  of  coal,  are  only  obtained  by  a  few 
plants,  although,  of  course,  possible  on  most  water-tube  plants. 
As  already  stated,  a  cylindrical  boiler  plant  will  run  on 
77 "5  to  80  per  cent,  under  good  conditions,  whilst  the  average 
is  60  per  cent.  It  should  be  remembered  also  that  the  wear 
and  tear  and  cost  of  upkeep  is,  on  the  average,  considerably 
greater  than  "  Lancashire  "  boilers. 

SMALL  CYLINDRICAL  BOILER  PLANT. 

There  are  hundreds  of  such  installations  scattered  about 
the  country  in  small  works,  hotels  and  hydros,  various  public 
institutions,  etc.,  with  an  average  coal  bill  of,  say,  10  to  20 
tons  a  week,  generally  consisting  of  one  or  two  small 
"  Lancashire  "  boilers  of  some  such  dimensions  as  1 5  to  20  ft. 
by  5  ft.  6  ins.  or  6  ft,  or  one  or  two  small  "Cornish"  boilers 
of  similar  dimensions,  hand-fired,  working  without  economisers, 
and  with  a  very  small  chimney. 

The  average  figures  for  these  plants  are  given  on  the  ad- 
joining page. 


RESULTS  AT  PRESENT  BEING  OBTAINED     31 


SMALL  CYLINDRICAL  BOILER  PLANT. 


i. 
2. 
3. 
4. 
5. 
6. 

7- 
8. 
g. 

10. 

ii. 

12. 


A.  Working-Day  Test. 
Number  of  boilers  working          .         .         . 
Grate  area  (total)        ...... 

Duration  of  test          ...... 

Price  of  coal  used  (per  ton  delivered) 
Amount  of  coal  used  .  . 

Analysis  of  coal—  B.Th.U  ..... 

it         n     i>       Ash        ..... 
Coal  burned  per  boiler  per  hour 

,,    burnt  per  square  foot  grate  area  per  hour  . 
Water  evaporated,  Ibs  ...... 

,,  .  ,,  per  boiler  per  hour 

,,  „  ,,    square  foot  grate  area  per 

hour    .... 

„  ,,  ,,    Ib.  of  coal 

Equivalent  evaporation  from  and  at  212°  F.  per 

Ib.  of  coal       .        .-  ...... 

Equivalent  evaporation  from  and  at  212°  F.  per 

1,000,000  B.Th.U  ...... 

Temperature  of  feed-water  before  economisers 
„  „          „  after  ,, 


18.  Percentage  of  coal  bill  saved  by  economisers      . 

19.  Draught  in  back  flues  of  boilers  .         . 

20.  ,,        „  chimney  base  ..... 

21.  Temperature  of  flue  gases  before  economisers     . 

22.  Number  of  economiser  tubes       .... 

23.  Temperature  of  flue  gases  after  economisers 

24.  Analysis  of  boiler  feed  water  — 

Degrees  permanent         .         ..        .         . 

,,        temporary         ..... 

25.  Percentage  CO2  in  flue  gases  (continuous  record 

on  combustion  recorder)          .         .         .         . 

26.  Steam  pressure  (average)  —  (a)  Gauge 

27.  ,,  „  „  (b)  Absolute     . 

28.  Temperature  of  saturation  of  steam 

29.  ,,  „  superheated  steam 

30.  Steam  or  power  used  as  auxiliary  to  production 

of  steam         ....... 

Thermal  efficiency  of  plant  — 

31.  (a)  Net  working  efficiency  of  plant  complete    . 

32.  (b)  Boilers  only        .         . 

33.  (c)    Economisers  only        .         .         .  '. 

34.  (d)  Superheaters    ,,      '     . 

35.  Cost  in  coal  to  evaporate  1000  gallons  of  water 

B.  Lon«  Check  Test  (One  Week}. 
(Say  Two  Shifts  per  24  Hours.) 

36.  Duration    ......         . 

37.  Price  of  coal  used  (per  ton  delivered)  .       '_'? 

38.  Amount  of  coal  used  .         .         .         .         .         . 

39.  Water  evaporated       .         .         .         . 

40.  „  ,,  per  Ib.  of  coal         .         .    '     . 

41.  Cost  in  coal  to  evaporate  1000  gallons  of  water 

42.  Coal  bill  for  20,000,000  gallons  evaporated  per 

annum  (say,  220  tons  of  coal  per  week) 


Ordinary  Average  Plant 

as  Generally  being 

WorkedTo-day. 

2  "  Lancashire  " 
40  sq.  ft. 
12  hours 

403. 
8326  Ibs. 

12,000 

10*5  per  cent. 
346-8  Ibs. 

i7'3    .. 

48,840   „ 

2,035    „ 

1017  ,, 
5  -86  Ibs. 
671  ,» 


110°  F. 

Nil 
(No  economisers) 

Nil 

0-50  in.  W.G. 
0-25   „       „ 

590°  F. 
No  economisers 

'(i.e.,  590°  F.) 

9° 
2° 

5  per  cent. 
70  Ibs. 

85    „ 
316-1°  F. 
No  superheat 

None 
54-1  per  cent. 

II  II  51 

Nil 


168  hours 

405. 

17-5  tons 
21,952  gals. 
5-60  Ibs. 


£31,886 


32  BOILER  PLANT  TESTING 

Such  small  boiler  installations  are  all  worked  more  or  less 
on  the  same  general  lines,  the  boiler  attendant  combining  the 
work  of  firing  the  boiler  with  other  duties,  so  that  the  attention 
received  is  not  continuous.  The  amount  of  coal  burnt  can  be 
taken  as  an  average  of  17  Ibs.  .*per  sq.  ft.  of  grate  area  per 
hour,  with  grates  4x5  ft.,  and  coal  as  before,  averaging 
12,000  B.Th.U.  per  pound.  As  regards  evaporation  this 
can  best  be  estimated  from  the  average  figures  of  an 
evaporation  of,  say,  575  Ibs.  of  water  at  110°  F.  per  Ib.  of 
coal,  corresponding  to  675  Ibs.  of  water  from  and  at  212°  F. 
Thus,  on  a  small  "  Lancashire  "  boiler  of  1 5  x  5  ft.  6  ins., 
the  figure  is  about  200  gallons  per  boiler  per  hour.  The 
draught  is  usually  about  0-5  in.  suction  water  gauge  in  the 
chimney  base,  the  chimney  being  small,  say,  averaging  50  to 
75  ft,  and  on  such  small  mechanical  draught  is  practically 
never  used. 

Also,  it  is  not  general  practice  to  use  steam  jet  furnaces 
on  these  plants,  but  if  present,  the  average  figure  for  the  steam 
consumption  of  the  jets  will  be  5  to  10  per  cent,  of  the  pro- 
duction of  the  plant,  with  a  corresponding  drop  in  efficiency. 
The  temperature  of  the  flue  gases  in  the  chimney  base  averages 
about  600°  F.  and,  as  before,  the  average  hardness  of  the 
water  can  betaken  as  11°  total  hardness.  Economisers  and 
superheaters  are  practically  never  installed,  but  if  present,  the 
saving  due  to  these  can  be  calculated  as  already  shown, 
namely,  11°  F.  rise  in  the  feed-water,  corresponding  to  I  per 
cent,  saving  in  the  coal  bill,  and  i°  F.  rise  in  the  superheat 
equals  0-05  per  cent,  saving.  The  net  working  efficiency  is 
about  54  per  cent,  and  probably  does  not  vary  more  than 
between  50  to  60  per  cent,  on  any  individual  plant. 

SMALL  VERTICAL  BOILER  PLANT. 

This  is  a  class  of  boiler  largely  used  in  many  industries, 
particularly  in  engineering  works,  by  builders  and  contractors, 
on  farms  and  in  small  establishments  of  every  description, 
and  the  average  results  being  obtained  are  as  given  on  the 
adjoining  page. 


RESULTS  AT  PRESENT  BEING  OBTAINED     33 


SMALL  VERTICAL  BOILER  PLANT. 


A.   Working-day  Test. 

1.  Number  of  boilers  working        .         . 

2.  Grate  area  (total)       .         .         .  . 

3.  Duration  of  test         .         .         .         . 

4.  Price  of  coal  used  (per  ton  delivered) 

5.  Amount  of  coal  used          .         .         .         .        . 

6.  Analysis  of  coal — B.Th.U.        .... 
7-  »»       i»     ,.       Ash        .         ... 

8.  Coal  burned  per  boiler  per  hour 

9.  ,,     burnt  per  square  foot  grate  area  per  hour 
10.  Water  evaporated,  Ibs.       .         . 

n.         ,,  ,,  per  boiler  per  hour 

12.  ,,  ,,  ,,    square   foot  grate  area 

per  hour   .         .         . 

13.  ,,  ,,  ,,    Ib.  of  coal     . 

14.  Equivalent  evaporation  from   and   at   212°  F. 

per  Ib.  of  coal       .         . 

15.  Equivalent  evaporation  from  and  at  212°  F.  per 

1,000,000  B.Th.U 

16.  Temperature  of  feed-water  before  economisers 

17.  ,,  ,,  ,,  after  ,, 


18.  Percentage  of  coal  bill  saved  by  economisers     . 

19.  Draught  in  back  flues  of  boilers 

20.  ,,         ,,  chimney  base  .... 

21.  Temperature  of  flue  gases  before  economisers  . 

22.  Number  of  economiser  tubes  , 

23.  Temperature  of  flue  gases  after  economisers 

24.  Analysis  of  boiler  feed  water — 

Degrees  permanent       ..... 
,,        temporary 

25.  Percentage  CO2  in  flue  gas  (continuous  record 

on  combustion  recorder)        .... 

26.  Steam  pressure  (average) — (a)  Gauge 

27.  ,,  ,,  „  (b)  Absolute   . 

28.  Temperature  of  saturation  of  steam 

29.  „  ,,  superheated  steam    . 

30.  Steam  or  power  used  as  auxiliary  to  produc- 

tion of  steam 
Thermal  efficiency  of  plant — 

31.  (a)  Net  working  efficiency  of  plant  complete  . 

32.  (b)  Boilers  only 

33.  (c)  Economisers  only       .         .         .         ,         . 

34.  (d)  Superheaters    ,, 

35.  Cost  in  coal  to  evaporate  1000  gallons  of  water 

B.  Long  Check  Test  (One  Week). 
(Say  Two  Shifts  per  24  Hours.) 

36.  Duration 

37.  Price  of  coal  used  (per  ton  delivered)        .        .. 

38.  Amount  of  coal  used         .        .        .        .       V 

39.  Water  evaporated     .         .         .         ... 

40.  ,,  ,,          per  Ib.  of  coal 

41.  Cost  in  coal  to  evaporate  1000  gallons  of  water 

42.  Coal  bill  for  20,000,000  gallons  evaporated  per 

annum  (say,  220  tons  of  coal  per  week) 

3 


Ordinary  Average  Plant 
as  Generally  being 
Worked  To-day. 


12  hours 

405. 

1353  Ibs. 
12,000 

10-5  per  cent. 
112-75  Ibs. 

7103  Ibs. 
591-9    ,» 


5-25  Ibs. 
6-01    ,, 

500-9     „ 
no0  F. 

Nil 
(No  economisers) 

Nil 

0-25  in.  W.G. 
0-30  „ 

800°  F. 
No  economisers 


9° 

2° 

5  per  cent. 
70  Ibs. 

85    „ 

316-1°  F. 

No  superheat 

None 

48-4  per  cent. 
Nil 

ti 

4o8*id. 


168  hours. 

405. 

4-5  tons. 
5141  gals. 
5-10  Ibs. 
42o-od. 


34  BOILER  PLANT  TESTING 

Vertical  boilers  are  usually  worked  with  a  short  metal 
chimney,  often  aided  by  a  steam  jet  in  the  chimney  base,  and 
hand  fixed. 

As  regards  evaporation,  this  can  be  taken  as  being  about 
5*25  Ibs.  of  water  at  116°  F.  per:ft>.  of  coal,  corresponding  to 
6  Ibs.  of  water  from  and  at  212°  F.  Very  roughly,  such 
boilers  burn  about  I  cwt.  of  coal  an  hour  and  evaporate  about 
60  gallons  of  water.  The  draught  in  the  baste  of  the  small 
chimney  is  usually,  say,  0*30  in.  suction  water  gauge,  but  can 
be  higher  if  a  steam  jet  is  used.  The  temperature  of  the  flue 
gases  is  usually  very  high,  averaging  800°  F.  whilst  the  per- 
centage of  CO2  is  about  5.  Such  plants  are  worked  without 
superheaters,  and  of  course,  economisers,  and  further,  steam 
jet  forced  draught  furnaces  are  rarely  applied.  The  average  net 
working  efficiency  can  be  taken  as  about  48  to  50  per  cent. 

EGG-ENDED  BOILER. 

This  boiler  was  invented  somewhere  about  the  year  1 780, 
probably  by  Richard  Trevithick,  Senior,  the  father  of  the 
more  famous  Richard  Trevithick  who  invented  the  " Cornish" 
boiler,  and,  as  already  stated,  there  are  actually  still  a  number 
of  egg-ended  boiler  plants  at  work  in  collieries.  How  many 
plants  are  still  running  it  is  not  possible  to  say,  but  the  num- 
ber seems  now  to  be  limited. 

The  average  figures  for  the  performance  can  be  taken  as 
given  on  the  adjoining  page. 

The  usual  dimensions  of  such  boilers  to-day  are  generally 
30  to  35  ft.  long  by  5  ft.  6  ins.  diameter,  with  a  blow-off 
pressure  of  40  to  60  Ibs.  They  are  built  high  up  on  the  top 
of  a  large  brick  firing  chamber,  so  that  the  bottom  of  the 
boiler  is  in  the  flames  from  the  fire  beneath,  an  arrangement 
known  as  a  "  flash  "  flue,  and  the  top  half  of  the  boiler  in  the 
open  air,  not  generally  insulated  in  any  way.  There  is  only 
one  large  firing  grate,  averaging  in  length  6  x  6  ft.  6  ins., 
and  in  width  about  4  ft.  6  ins.,  and  the  flames  travel  along  the 
bottom  of  the  boiler  and  straight  up  to  the  chimney,  which 
is  placed  just  behind  the  boilers.  The  height  of  the  chimney 


RESULTS  AT  PRESENT  BEING  OBTAINED     35 


EGG-ENDED  BOILER  PLANT. 

A.   Working-Day  Test. 

1.  Number  of  boilers  working          . 

2.  Grate  area  (total) 

3.  Duration  of  test 

4.  Price  of  coal  used  (per  ton  delivered) 

5.  Amount  of  coal  used  ..... 

6.  Analysis  of  coal— B.Th.U 

7-          .»        M     »       Ash 

8.  Coal  burned  per  boiler  per  hour 

g.      ,,     burnt  per  square  foot  grate  area  per  hour   . 

10.  Water  evaporated,  Ibs 

11.  ,,  ,,  per  boiler  per  hour 

12.  „  ,,  ,,    square  foot  grate  area  per 

hour 

13.  „  ,,  „   lb.  of  coal 

14.  Equivalent  evaporation  from  and  at  212°  F.  per 

lb.  of  coal 

15.  Equivalent  evaporation  from  and  at  212°  F.  per 

1,000,000  B.Th.U. 

16.  Temperature  of  feed-water  before^  economisers 

17.  „  ,,  „         after  „ 

18.  Percentage  of  coal  bill  saved  by  economisers 

19.  Draught  in  back  flues  of  boilers 

20.  „         ,,  chimney  base  ..... 

21.  Temperature  of  flue  gases  before  economisers 

22.  Number  of  economiser  tubes       . 

23.  Temperature  of  flue  gases  after  economisers 

24.  Analysis  of  boiler-feed  water — 

Degrees  permanent 

„        temporary          .         .         .         . 

25.  Percentage  CO2  in  flue  gas  (continuous  record 

on  combustion  recorder)          .... 

26.  Steam  pressure  (average)  — (a)  Gauge 

27.  ,,  „  „         —(b)  Absolut:      . 

28.  Temperature  of  saturation  of  steam    . 

2g.  ,,  ,,  superheated  steam       .         .       .  , 

30.  Steam  or  power  used  as  auxiliary  to  production 

of  steam 

Thermal  efficiency  of  plant — 

31.  (a)  Net  working  efficiency  of  plant  complete 

32.  (b)  Boilers  only         .'.. ' 

33.  (c)   Economisers  only 

34.  (d)  Superheaters    ,,  ..... 

35.  Cost  in  coal  to  evaporate  1000  gallons  of  water 

B.  Long  Check  Test  (One  Week). 
(Say  Two  Shifts  per  24  Hours.) 

36.  Duration , 

37.  Price  of  coal  used  (per  ton  delivered) 

38.  Amount  of  coal  used 

3g.  Water  evaporated 

40.  „  ,,          per  lb.  of  coal 

41.  Cost  in  coal  to  evaporate  1000  gallons  water 

42.  Coal  bill  for  20,000,000  gallons  evaporated  per 

annum  (say,  220  tons  of  coal  per  week) 


Ordinary  Average  Plant 
as  Generally  being 
Worked  To-day. 

4 

112  sq.  ft. 
12  hours 

408. 
30,240  Ibs. 

12,000        7y  ;  o  f> 
io'5  per  cent. 

630  Ibs.         £  1  / 

22'5    ,, 

112,800  Ibs. 
2,35°  >, 

83-9       „ 
373       „ 

4-26   „ 

355  Ibs. 
110°  F. 

Nil 
(No  economisers) 

Nil 
o'go  in.  W.G. 

I'OO    ,,        ,, 

850°  F. 
No  economisers 

"(i.e.t  850°  F.) 

12° 

5° 

3-75  per  cent. 

55  Ibs. 

70   „ 

320-9°  F. 

No  superheaters 

Nil 

34-3  per  cent. 
Nil 


168  hours 

4cs. 

1    82  tons 
67,050  gals. 
3-65  Ibs. 
587'od. 


36  BOILER  PLANT  TESTING 

usually  averages  100  to  140  ft.  The  firing  is  carried  out  by 
hand,  and  the  fire-bars  generally  are  of  a  very  heavy  type, 
with  very  poor  air-space.  Nothing  in  the  way  of  steam  jet 
bars  or  other  appliances  seems  to  be  used  in  connection  with 
the  firing  of  this  type  of  boiler.  Such  a  plant  was  the 
standard  colliery  practice  not  so  many  years  ago.  In  collieries 
the  boiler  feed-water  is  heated  by  the  exhaust  steam  of  the 
winding  and  other  engines,  and  generally  goes  into  the 
boilers  at  about  150°  to  160°  F.  average.  As  already  ex- 
plained, however,  a  given  temperature  of  110°  F.  has  been 
taken  for  the  feed- water  for  comparison,  and  the  results 
altered  by  calculation.  This,  of  course,  does  not  alter  the 
essential  figure  of  the  efficiency  of  the  boiler  itself. 

In  a  typical  egg-ended  boiler  of  30  to  35  ft.  long  and 
5  ft.  6  ins.  diameter,  the  amount  of  coal  burnt  is  almost  the 
same  as  a  "Lancashire"  boiler  30  x  8  ft,  averaging  22*5 
Ibs.  of  coal  per  square  foot  of  grate  area  per  hour.  The 
amount  of  the  evaporation  calculated  to  1 10°  F.  is  only  about 
250  gallons,  practically  one-third  of  that  of  a  " Lancashire" 
boiler  30  x  8  ft.  The  water,  at  110°  F.,  evaporated  per 
Ib.  of  coal  is  only  about  375  Ibs.,  corresponding  to,  say,  4*5 
Ibs.  from  and  at  212°  F.  The  draught  on  such  boilers  is 
usually  good,  because  the  chimneys  used  are  a  fair  height,  as 
already  stated,  and  the  flue  gas  temperature  is  very  high,  say 
850°  F.,  because  the  flames  merely  go  along  the  bottom  of 
the  boiler  and  straight  up  the  chimney. 

The  figure  for  CO2  is  very  low,  only  about  4  per  cent, 
because  of  the  large  open  grates  and  the  almost  invariably 
bad  quality  of  the  brickwork  due  to  the  abnormal  expansion 
and  contraction.  The  net  working  efficiency  is  about  35 
per  cent,  a  shocking  figure,  and  statements  such  as  6-5  to 
8-5  Ibs.  of  water  from  and  at  212°  F.  per  Ib.  of  coal  for  egg- 
ended  boilers  are  ridiculous  when  applied  to  the  present 
average  working  conditions. 

These  average  figures  for  the  various  types  of  boilers,  ex- 
pressed in  one  table  for  easier  comparison,  are  as  follows : — 


RESULTS  AT  PRESENT  BEING  OBTAINED     37 


•  -a  fe  So 

IflJ 


- 

to       g 


•- 

S  u'o  S 
W^03  > 


in  2  CO 

I     i«*pp>Ou—   roOO  CTiM°O.M-Hrt         -<i 

I     I    "mvo  O  £  '"'S  0,5  ^  o^vo'q'lj       00 

a  g  a 


oo  en  tx      ^N0S->QO       o\  N  o  o  r  0  —       .M  ,H  -3  — 

^  ^  3  ^^  s  M  o  's  °  *  a       ««  ^^s  *8   ^  s'c  'c 

CO          M  u->  CO 


. 
81 


o  n"  « 
0  rtCU 


•M  o'coik-M  2^-50  1QJQ 
M^CO          vS^O0       «-o 


O_0\>r>CC^(0 
^^^^^'M       M»^« 


p*;*-py»\«ci 

^g^^^^ 

00  M  ts 


-«0->oQ    w 

JOM  «-g  o  o  5      M 

10  g 


p  o  r1-  P 

' 


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covo 


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8.    S.S.8.S, 


S      * 


^^28  '6  -"S^-0 

.«  61S-:  §  'PI 

kUi.i-  1  '^.§ 

- 


« 


BOILER  PLANT  TESTING 


The  great  importance  of  scientific  methods  in  boiler  plant 
management  will  be  realised  by  the  following  simple  coal 
balance  sheet  for  Great  Britain,  being  approximate  figures 
allowing  for  abnormal  circumstances  due  to  wars,  strikes,  ex- 
change troubles  and  other  complications. 

GREAT  BRITAIN. 

(Average  annual  figures  which   will   probably  apply  more  or  .less  to  the  next 

few  years.) 


so  tons 

Coal  Disposal  — 

(A)  Exported,  25  per  cent.,  as  follows  :  — 

Tons. 

Per  Cent, 
of  Total 
Coal 
Raised. 

i.  Sold  to  the  colonies  and  foreign  countries     . 

41,875,000 

1675 

2.      ,,     ,,  ocean-going  steamers        .         .         . 

13,750,000 

5-50 

3.      ,,     ,,  foreign  countries  as  coke 

3,125,000 

1-25 

4.      ,,     ,,        „            ,,           in      the    form    of 

manufactured  fuel  (briquettes,  etc.)  . 

1,875  ooo 

0'75 

O'7S 

/  j 

Total 

(B)  Home  Consumption,  75  per  cent.,  as  follows  : — 

6.  Steam  generation  : — 

(a)  Powei 

(b)  Low  i 

7.  I  omestic 

8.  Coke  from  coke  ovens 

9.  Gas  works    . 

10.  Railways 

11.  General  purposes 

Total 


62,500,000  25'OO 


30SCS  . 

60,000,000 

24-0 

are  purposes 

30,000,000 

I2'O 

. 

35,000,000 

I4-0 

/ens  . 

20,000,000 

8-0 

. 

18,000,000 

7-20 

. 

15,000,000 

6-0 

4-80 

*r  v 

187,500,000        75*00 


That  is  to  say,  we  consume  90,000,000  tons  of  coal  per 
annum,  36  per  cent,  of  the  total  coal  raised,  or  48  per  cent,  of 
the  home  consumption,  for  the  one  operation  of  steam  genera- 
tion. 

In  general,  of  this  huge  amount,  6,500,000  tons  are  being 
burnt  at  say  70  per  cent,  efficiency  or  over,  13,000,000  tons 
at  say  65  to  70  per  cent,  efficiency,  15,500,000  tons  at  say 
60  to  65  per  cent,  efficiency,  21,500,000  tons  at  55  to  60  per 
cent,  18,000,000  tons  at  50  to  55  per  cent.,  and  15,500,000 
tons  at  less  than  50  per  cent. 


RESULTS  AT  PRESENT  BEING  OBTAINED     39 

Now  it  is  possible,  in  averages,  to  work  steam  boiler  plants 
at  7  5  Per  cent-  net  working  efficiency. 

This  is  not  a  theoretical  or  fantastic  figure,  but  a  reasonable 
and  practical  basis,  such  as  quite  a  number  of  firms  have 
already  obtained  by  the  exercise  of  care  and  common  sense, 
and  with  ordinary  and  well-known  plant  machinery  and 
appliances.  Thus,  out  of  the  400  plants  tested,  2  plants  are 
working  at  80  per  cent,  efficiency  or  over,  and  9  plants  at 
75  per  cent,  or  over,  whilst  17  plants  are  working  at  70  per 
cent,  or  over.  There  is  obviously  something  seriously  wrong 
with  our  general  methods  of  steam  generation  when  69  plants 
are  actually  working  at  less  than  50  per  cent,  efficiency,  a 
disgraceful  performance,  whilst  another  80  plants  are  below 
55  per  cent.,  and  altogether  245  plants  are  below  60  per  cent. 
We  can  take  almost  any  industry  in  the  country  and  if  50 
boiler  plants  are  tested,  it  will  be  found  that  the  best  plant 
will  be  75  to  80  per  cent,  efficiency,  and  the  figures  can  be 
tabulated  one  under  the  other,  until  the  lowest  plant  is  not 
more  than  45  per  cent,  or  so.  It  is  quite  a  common  experience 
to  find  two  works  in  the  same  industry  working  under  identical 
conditions,  even  in  the  same  street,  where  the  boiler  plant  of 
one  is,  say,  65  per  cent,  efficiency,  and  the  other  55  per  cent., 
that  is,  the  coal  bill  of  one  works  is,  say,  1 5  per  cent,  less  than 
the  other,  so  that  if  one  firm  is  burning  10,000  tons  a  year, 
the  other  man  is  only  burning  8500  tons  for  the  same  duty. 

The  general  reason  for  this  lamentable  state  of  affairs  is 
the  almost  complete  failure  to  realise  that  steam  generation  is 
an  important,  interesting,  and  intricate  branch  of  applied 
science,  and  that  in  nearly  all  industries  there  is  more  money 
to  be  saved  in  the  boiler  house  than  in  any  other  section  of 
the  establishment.  Modern  scientific  principles  of  steam 
generation  comprise  two  distinct  sections,  namely,  efficient 
design  and  equipment  of  the  boiler  plant,  and  scientific  methods 
of  control  of  the  working  of  the  plant,  so  that  the  best  results 
are  obtained.  The  boiler  plants  of  Great  Britain  are  very 
defective  in  both  these  sections,  but  the  second  is  much  the 


4o 


BOILER  PLANT  TESTING 


more  important  of  the  two,  and  the  lack  of  interest  displayed 
in  the  intelligent  working  of  boiler  plant  could  not  be  better 
illustrated  by  the  fact  that  there  is  no  recognised  method  in 
the  country  of  testing  the  performance  of  a  plant  It  should 
be  the  special  object  of  an  International  Code  to  encourage 
the  continual  testing  and  scientific  control  of  boiler  plant  by 
making  the  Code  eminently  practical.  I  will,  of  course, 
discuss  this  second  section  in  detail  in  the  next  chapters  of 
this  book,  but  it  will  not  be  without  interest  to  state  here 
briefly  the  circumstances  as  regards  the  lack  of  proper  equip- 
ment on  the  boiler  plants  of  Great  Britain. 

The  boiler  itself  is  of  comparatively  little  importance,  and 
a  "  Lancashire  "  or  other  cylindrical  boiler  plant  will  give 
practically  as  good  results  as  a  water-tube  boiler  plant. 
There  is,  however,  a  great  lack  of  economisers.  In  the  250 
plants,  as  already  seen,  the  average  saving  due  to  the  econo- 
misers was  only  7' I  per  cent,  of  the  coal  bill.  The  detailed 
figures  for  the  economiser  performance  I  have  given  in 
''Engineering,"  1st  November,  1918  ("Exact  Data  on  the 
Running  of  Steam  Boiler  Plants,  No.  I,  Economisers"),  as 
follows  : — 

TABLE  SHOWING  RESULTS  OF  WORKING  WITH  ECONOMISERS. 


Average 
Temperature 
of  Feed-water. 

Average 
Temperature 
of  Flue  Gases. 

Draught  in 
Inches.    W.G. 

Steam 

Total 

Division  Accord- 
ing to  Saving 
Obtained. 

No. 
of 

Plants. 

Pres- 
sure- 
Gauge. 

T  he; 

Evapora- 
tion on 
Plant 
per  Hour. 

No.  of 
Tubes 
on 
Plant. 

Before. 

After. 

Before. 

After. 

Chimney  Side 
Flue  Base  or 

Downtake  of 

.LiDS. 

°F. 

°F. 

°F. 

°F. 

Blowers. 

per 
Sq.  In. 

Lbs. 

No  economiser 

at  all    . 

95 

— 

— 

— 

— 

— 

— 

— 

— 

— 

Less  than  5  °/ 

14 

134 

172 

568 

371 

0-85 

0-41 

80 

I7,6i6'o 

228 

5  to  7J  °/0        . 

15 

123 

194 

576 

423 

o'6i 

0'35 

79 

15,340-0 

203 

7i  to  10  °/0      . 

23 

IIQ 

26l 

549 

374 

0-74 

0'33 

IOO 

16,630  o 

231 

10  tO  12^  %      . 

33 

118 

243 

583 

403 

0-88 

0-39 

106 

29,723-0 

401 

iajtoi5°/0    . 

46 

no 

262 

584 

379 

0-99 

0-41 

99 

19,760-0 

280 

Over  15  °/0       . 

24 

170 

284 

610 

375 

i'35 

0-60 

119 

23,497'° 

392 

Total     . 

250 

RESULTS  AT  PRESENT  BEING  OBTAINED     41 

That  is,  95  plants  had  no  means  of  utilising  the  waste  heat 
of  the  flue  gases,  and  it  will  probably  not  be  an  exaggeration 
to  say  that  25  per  cent,  of  the  boiler  plants  of  Great  Britain 
have  no  economisers  at  all. 

Taking  now  the  1 5  5  plants  fitted  with  economisers,  the 
average  saving  obtained  on  these  plants  was  11*4  per  cent,  of 
the  coal  bill.  Only  24  plants  or  17  per  cent,  of  plants  fitted 
with  economisers  were  saving  I  5  per  cent,  or  over  of  the  coal 
bill,  and  only  12  plants  17  per  cent,  or  over. 

It  is  the  general  rule  to  install  economisers  on  rule-of- 
thumb  lines  such  as,  for  example,  72,  96  or  120  tubes  per 
boiler,  quite  irrespective  of  the  evaporation.  For  this  reason, 
and  also  because  the  draught  is  apt  to  be  choked,  there  is  in 
general  not  sufficient  tubes  for  the  best  results.  An  average 
saving  of  say  7-J  per  cent,  of  the  coal  bill  instead  of  about 
17-5  per  cent,  which  ought  to  be  obtained,  means  a  national 
loss  of  about  10  per  cent,  in  the  coal  bill,  or  9,000,000  tons  of 
coal  per  annum.  Also  practically  no  use  is  made  of  feed-water 
heaters,  so  that  any  exhaust  steam  available,  such  as  that  from 
the  boiler  feed  pump,  economiser  engine,  mechanical  draught 
engine,  etc.,  can  be  usefully  employed  in  heating  the  feed-water 
on  the  way  to  the  economiser.  In  averages,  something  like 
3  per  cent,  of  the  coal  bill  is  lost  in  this  way,  say,  2,700,000 
tons  per  annum. 

Also,  there  is  a  considerable  annual  loss  due  to  scale  in  the 
feed-water,  although  it  is  difficult  to  express  this  loss  in  money. 

The  average  hardness  of  the  boiler  feed-water  of  the  United 
Kingdom  is  about  1 1  grains  per  gallon,  and  taking  the  average 
figure  of  6'5  Ibs.  of  water  evaporated  per  Ib.  of  coal,  this 
corresponds,  at  90,000,000  tons  of  coal  per  annum,  to  an 
evaporation  of  580,000,000  tons  of  water  yearly,  and  a  de- 
position in  the  boilers  of  the  United  Kingdom  of  100,000  tons 
of  scale  and  other  solid  material  per  annum,  nearly  2000  tons 
a  week.  It  is  impossible  to  get  the  best  results  on  any  boiler 
plant  with  scale  in  the  boilers,  and  we  do  not  pay  anything 
like  enough  attention  to  the  purification  of  the  feed-water, 
either  by  a  water  softening  plant  or  otherwise. 


BOILER  PLANT  TESTING 


As  regards  mechanical  stoking,  probably  about  25  per 
cent,  or  22,500,000  tons,  is  burnt  per  annum  by  means  of 
mechanical  stokers  instead  of  hand-firing.  I  dealt  very  fully 
with  the  question  of  mechanical  versus  hand  stoking  in  a 
recent  paper,  "  Exact  Data  on  the  Performance  of  Mechanical 
Stokers  as  Applied  to  '  Lancashire '  and  other  Narrow-flued 
Boilers,"  read  before  the  Institution  of  Mechanical  Engineers 
on  the  I  Qth  March,  1920.  In  this  paper  was  given  the  detailed 
figures  for  the  performance  of  80  "  Lancashire  "  boiler  plants, 
mechanically  fired.  The  average  net  working  efficiency  of 
these  80  plants  was  approximately  59  per  cent,  the  boilers 
only  being  53  per  cent.  In  the  250  tests  already  mentioned 
76  per  cent,  of  the  plants  were  hand-fired  and  24  per  cent, 
mechanical,  and  the  figures  can  be  divided  as  follows  ("Pro- 
ceedings of  the  Institution  of  Mechanical  Engineers,"  March, 
1920,  p.  275):— 


80  Plants 
Mechanically  Fired. 

250  Plants  (76  Per  Cent. 
Hand  Firing  and  24  Per 
Cent.  Mechanical  Firing). 

No.  of 
Plants. 

Per  Cent. 

No.  of 
Plants. 

Per  Cent. 

Over  80  per  cent.    . 
75  to  80     , 

I 
2 

1-25 
2*50 

2 
9 

0-8 
3-6 

70  „  75     , 
65  „  70     , 
60  „  65     , 

2 
II 

16 

15 

16 

2-50 

21-25 

2O-OO 

18-75 
20-OO 

13 
30 

£ 

47 
43 

I2'0 

17-6 

24-8 

18-8 
17-2 

55  ,»  60     , 
5°  „  55     » 
Less  than  50  per  cent. 

80 

lOO'OO 

250 

lOO'O 

The  average  net  working  efficiency  of  350  hand-fired 
plants  is  about  60  to  62  per  cent.  So  that  on  these  figures, 
mechanical  stoking  is  giving  actually  less  efficiency  than  hand 
stoking.  In  my  opinion,  if  all  the  plants  in  Great  Britain 
are  considered,  there  is  little  or  no  difference  between  me- 
chanical and  hand  stoking,  and  it  cannot  be  said,  therefore, 


RESULTS  AT  PRESENT  BEING  OBTAINED      43 

that  we  are  losing  much  coal,  because  only  25  per  cent,  of 
boiler  plants  are  equipped  with  mechanical  stokers. 

Another  cause  of  loss  is  that  full  advantage  is  not  taken  of 
mechanical  draught,  and  probably  about  90  per  cent,  of  the 
boiler  plants  of  Great  Britain  rely  on  natural  or  chimney 
draught.  The  chimney,  unless  built  very  high,  and  good 
quality  coal  is  used,  is  an  out-of-date  and  unscientific  con- 
trivance as  a  draught  producer,  and  other  things  being  equal, 
the  draught  simply  depends  on  the  temperature  in  the  base, 
that  is,  the  more  heat  is  lost  the  better  is  the  draught.  When 
an  economiser  is  installed  to  prevent  this  heat  loss,  the  draught 
is  choked  because  the  temperature  of  the  exit  gases  is  reduced. 

The  extent  of  this  draught  reduction  is  seen  by  the 
following  actual  example  : — 

Brick  chimney  170  ft.  high  with  a  temperature  in  the  base 
of  600°  F.  working  without  economisers.  The  temperature  of 
the  gases  in  a  brick  chimney  is  reduced  about  2°  F.  for  every 
3  ft.  in  height  because  of  the  cooling  action  of  the  outside  air, 
so  that  the  average  temperature  of  the  hot  gases  in  the  whole 
of  the  chimney  from  top  to  bottom  will  be  about  544°  F.,  taking 
the  outside  air  as  60°  F. 

The  draught  in  the  chimney  base  under  these  conditions, 
expressed  as  inches  suction  water  gauge,  is  very  nearly  given 
by  the  following  formula  (which  includes  friction  losses) : — 


where  P  =  inches  water  gauge 

H  =  Ht.  in  feet  of  chimney  above  the  firing  level 
T  =  the  mean  absolute  temperature  of  the  chimney  gases 
/  =  absolute  temperature  of  the  chimney  gases 

P  _  x  (      7'6  7'9       \ 

\6o  +  461  "  544  +  46 1/ 
/7-6        7'9  \ 

=  17° x  \ja  -  TooV 

=  170  x  (0*01458  -  0-00786) 
=  171   x  (000672) 

=  1*14  in.  W.G.,  which  equals  about  0*65  -  0-85  in. 
W.G.  in  the  side  flues  of  a  "  Lancashire  "  boiler. 


44  BOILER  PLANT  TESTING 

If  now  we  install  economisers  to  reduce  the  coal  bill,  say, 
17*5  Per  cent.,  the  temperature  of  the  gases  in  the  chimney 
base  will  be  reduced  from  600°  F.  to,  say,  350°  F.  This  will 
correspond  to  an  average  temperature  in  the  whole  of  the 
chimney  of  about  294°  F.,  and  the  draught  will  be  as  follows  : — 


7'9\ 
T/ 


/     7- 
\6o  + 


=  i7o' 


461       294  +  46  1 
7-6       7-9  \ 


=  170  (0-01458  -  0-01046) 

=  070  in.  W.G.,  which  equals  about  0-35  in.  W.G.  in 
the  side  flues  of  a  "  Lancashire  "  boiler. 

In  the  250  tests  the  155  plants  fitted  with  economisers 
show  an  average  drop  in  the  flue  gas  temperature  from  581° 
to  389°  F.  whilst  the  draught  averages  0-97  in.  W.G.  in  the 
chimney  base,  and  is  reduced  to  0-45  in.  in  the  side  flue  or 
downtake.  The  installation  of  economisers  therefore  causes 
a  serious  reduction  in  the  draught  and,  for  example,  on  theo- 
retical grounds,  if  more  economisers  were  installed,  and  the 
saving  increased  to  say  22*5  per  cent,  of  the  coal  bill  with 
the  gases  cooled  to  say  250°  F.  the  draught  would  be  so 
reduced  that  hardly  any  coal  would  be  burnt 

Although,  as  already  stated,  chimney  draught  works  very  well 
with  a  high  chimney  and  good  quality  fuel,  so  that  say  0*35  in. 
W.G.  is  sufficient  draught  in  the  side  flues,  the  great  majority 
of  boiler  plants  do  not  possess  these  advantages.  Consequently, 
in  spite  of  the  fact  that,  in  general,  sufficient  economisers  are 
not  installed,  hundreds  of  boiler  plants  have  to  work  with  the 
economiser  bye-pass  damper  partly  open  to  allow  some  of  the 
hot  gases  to  go  right  up  the  chimney,  so  as  to  provide  sufficient 
draught  to  work  the  plant.  The  main  advantage  of  mechanical 
draught  (forced  or  induced)  is  that  the  draught  is  quite  in- 
dependent of  the  flue  gas  temperature,  being  provided  by  the 


RESULTS  AT  PRESENT  BEING  OBTAINED     45 

engine  or  motor  driving  the  fan,  which  takes  the  equivalent 
of  about  2*5  per  cent,  of  the  steam  production  of  the  plant. 
Consequently,  the  full  amount  of  heat  can  be  extracted  by  the 
economisers,  and  theoretically  the  flue  gas  exit  temperature 
could  be  reduced  to  213°  F.  to  absorb  all  the  heat,  and  still 
retain  all  the  water  in  the  flue  gases  as  steam. 

A  large  number  of  boiler  plants  (93  plants  out  of  the 
250  tested)  probably  about  35  per  cent,  of  the  plants  of  the 
country,  are  working  with  some  form  of  steam  jet  furnace, 
either  hand  or  mechanically  fired,  which  can  be  called  a 
variation  of  forced  draught.  Most  of  these  steam  jet  furnaces 
are  working  in  conjunction  with  natural  or  chimney  draught 
but  a  few  have  mechanical  induced  draught. 

The  amount  of  steam  used  by  the  steam  jets  averages 
about  6-5  per  cent,  of  the  production  of  the  plant  and  is  much 
too  high.  I  published  in  "Engineering,"  i6th  January,  1920 
("  Exact  Data  on  the  Running  of  Steam  Boiler  Plants,  No,  3. 
The  amount  of  Steam  Used  by  Steam  Jets "),  the  results  of 
investigation  carried  out  into  the  working  of  130  boiler  plants 
fitted  with  steam  jet  furnaces,  eleven  different  types  of  hand- 
fired  furnace  and  eight  different  types  of  mechanically  fired, 
comprising  437  boilers  with  a  coal  bill  of  about  1,000,000  tons 
per  annum.  The  results  are  tabulated  on  page  46. 

It  is  generally  assumed  that  the  amount  of  steam  used  by 
steam  jets  is  small,  say  I  to  2  per  cent,  of  the  production,  but 
it  will  be  obvious  that  these  figures  are  quite  erroneous,  and 
the  amount  is  much  more  than  is  generally  realised. 

One  of  the  most  striking  facts  is  the  enormous  difference 
between  the  amounts  of  steam  used  by  these  steam  jets.  Thus, 
the  lowest  figure  obtained  was  0-50  per  cent,  of  the  production, 
and  the  highest  21-4.  The  differences  on  different  plants 
using  the  same  make  of  apparatus  are  almost  as  remarkable. 

Of  the  whole  1 30  plants,  twenty-nine  have  coal  bills  of  over 
;£iooo  per  annum  incurred  by  the  use  of  steam  jets  alone, 
whilst  the  number  of  plants  with  coal  bills  of  ^500  or  over  is 
forty-seven. 


46 


BOILER  PLANT  TESTING 


The  great  cost  incurred  in  average  cases  in  the  running  of 
steam  jets  is  not  realised.     Thus,  taking  an  average  sized  boiler 

AMOUNT  OF  STEAM  USED  BY  STEAM  JETS. 

AVERAGE  RESULTS  FOR  HAND  FIRING. 
(Net  Average  6;6  Per  Ceril  of  the  Production.) 


Type  of 
Apparatus. 

Number  of 
Plants  Fitted. 

Total  Number 
of  Boilers. 

Percentage  of 
Production  of 
the  Plant  us^d 
by  Jets. 

Total  Coal 
Bill  of  the 
Plants  per 
Annum. 
Tons. 

Total  Coal 
Bill  used  by 
the  Jets. 
Tons. 

A. 

6 

17 

7-6 

20,200 

1535-2 

B. 

4 

7 

4*5 

15,400 

693-0 

C. 

3 

6 

7'3 

9,234 

674-0 

D. 

18 

60 

6'3 

137.005 

8361-5 

E. 

7 

22 

8-1 

55,450 

4491-4 

F. 

2 

3 

3"2 

5,850 

187-2 

G. 

2 

4 

5'0 

6,600 

330-0 

H. 

2 

6 

7*7 

14,400 

noS'o 

I. 

3 

6 

4  '4 

8,525 

375'i 

J. 

I 

2 

15-25 

4,000 

610-0 

K. 

6 

16 

5*9 

35,346 

2079-5 

Total 

54 

149 

312,010 

207157 

AVERAGE  RESULTS  FOR  MECHANICAL  FIRING. 
(Net  Average  6-7  Per  Cent,  of  the  Production.) 


Type  of  Apparatus. 

Number  of 
Plants 
Fitted. 

Total 
Number  of 
Boilers. 

Percentage  of 
Production 
of  the  Plant 
used  by  Jets. 

Total  Coal 
Bill  of  the 
Plants  per 
Annum. 
Tons. 

Total  Coal 
Bill  used  by 
the  Jets. 
Tons. 

Sprinkling  Stoker. 

A. 

25 

73 

5'0 

140,345 

7017-2 

B. 

16 

45 

5*25 

95,550 

5016-4 

C. 

7 

23 

5'o 

30,070 

I503-5 

Coking  Stoker. 

A. 

4 

12 

2-3 

21  050 

484-I 

B. 

i 

3 

13-8 

5,750 

793-5 

C. 

13 

66 

8-0 

221,950 

17756-0 

D. 

i 

3 

7-2 

4,900 

352-8 

E. 

9 

63 

7*5 

185,250 

i3»93'7 

Total 

76 

288 

704,865 

46817-2 

plant  of  six  "Lancashire"  boilers,  burning  say  12,000  tons  of 
coal  per  annum,  equivalent  to  £18,000  per  annum,  with  coal 


RESULTS  AT  PRESENT  BEING  OBTAINED     47 

at  an  average  price  of  303.  per  ton.  The  cost  of  an  ordinary 
steam  jet  apparatus  hand-fired  would  be  about,  say,  £100  per 
boiler,  equal  to  £600  for  the  plant. 

Taking  the  average  figure  of  6'6  percent,  of  the  steam  pro- 
duction used  by  the  jets,  this  corresponds  to  £i  188  per  annum 
as  the  cost  cf  the  steam  used,  equal  to  buying  an  entirely  new 
set  of  steam  jet  apparatus  for  the  whole  of  the  six  boilers  about 
every  six  months. 

For  a  similar  plant  a  mechanical  stoker  equipment  would 
cost  about  double,  say,  £2000,  and  in  this  case  at  6-5  per 
cent,  of  the  steam  production,  this  would  be  equivalent  to 
replacing  the  whole  of  the  stokers,  say,  every  eighteen  months. 
In  addition,  also,  in  the  latter  case  the  cost  of  upkeep  of  the 
stokers  has  to  be  taken  into  account,  whereas  the  hand-fired 
steam  jet  apparatus  has  the  advantage  that  the  fire-bars  last 
a  very  long  time  because  of  the  "  cooling  "  action  of  the  steam. 

Assuming  that  35  per  cent,  of  the  boiler  plants  of  the 
United  Kingdom  are  fitted  with  steam  jet  furnaces,  this  corre- 
sponds to  31,500,000  tons  of  coal  burnt  per  annum,  and  at 
6'6  per  cent,  of  the  production  of  the  plant,  is  equal  to 
about  2,000,000  tons  of  coal  used  per  annum  for  the  sole 
purpose  of  steam  generation  to  supply  steam  jets.  Assuming 
that  the  steam  jet  furnace  is  the  right  method  for  burning 
35  per  cent,  of  the  coal  used  for  steam  generation,  then  with 
proper  care  and  attention,  the  amount  of  steam  used  ought  to 
be  cut  down  to  3*5  per  cent,  of  the  production,  say  within  the 
limits  of  I  '5  to  4  per  cent.  That  is  to  say,  by  the  careless 
use  of  steam  jets,  and  the  use  of  a  number  of  furnaces  of  bad 
design,  we  are  wasting  per  annum  about  1,000,000  tons  of 
coal.  The  question  of  the  advisability  of  using  steam  jets  at 
all  is  a  matter  of  opinion,  but  in  certain  cases,  such  as  for 
coke  and  coke  breeze,  and  some  varieties  of  refuse  coal,  they 
are  very  useful.  Roughly,  I  should  say  that  under  existing 
conditions  of  burning  raw  coal,  about  10  per  cent,  of  the 
boiler  plants  of  the  country  are  suitable  for  hand-fired  steam  jet 
furnaces,  whilst  the  question  of  mechanical  firing  is  very  open. 


48  BOILER  PLANT  TESTING 

Finally,  as  regards  superheaters,  we  do  not  make  anything 
like  the  proper  use  of  superheated  steam.  The  value  of 
superheating  for  fuel  economy  is  in  two  directions,  first,  that 
of  partial  superheat  to,  say,  75°  F.  to  reduce  condensation 
losses  in  the  steam  pipe  circuits,.*and,  secondly,  that  of  high 
superheat  up  to  200°  F.  to  improve  the  efficiency  of  the  steam 
engine  or  turbine.  Out  of  the  250  plants  tested,  only  eighty 
were  fitted  with  superheaters,  and  of  these  eighty  plants  only 
twenty-five  plants  were  completely  equipped,  so  that  the 
average  amount  of  superheat  on  the  eighty  plants  was  50°  F, 
(316°  F.  temperature  of  saturation  to  366°  F.  on  the  super- 
heater). 

It  will  not  be  an  exaggeration  to  say  that  5  per  cent,  of 
the  coal  bill,  4,500,000  tons  per  annum,  is  lost  because  of  the 
failure  to  realise  the  value  of  superheating. 

Finally,  I  should  like  to  point  out  that  Great  Britain  is 
probably  no  worse  in  respect  of  inefficient  steam  generation 
than  any  other  country,  and  this  deplorable  state  of  affairs 
seems  to  exist,  for  example,  in  America  and  France  also.  I 
have  examined  about  forty  boiler  plants  in  France  and 
judging  from  this  short  experience,  and  from  information 
contained  in  French  engineering  literature,  it  would  seem 
that  the  average  net  working  efficiency  of  the  boiler  plants  of 
France  is  not  much  more  than  60  per  cent.,  and  certainly  not 
over  65  per  cent.  I  have  no  personal  experience  of  boiler 
plants  in  America,  but  judging  by  the  American  engineering 
literature,  especially  in  connection  with  the  efforts  made  for 
fuel  economy  during  the  war,  it  would  appear  that  in  America 
also  the  average  net  working  efficiency  of  boiler  plants  does 
not  exceed  60  per  cent. 

It  is  painfully  interesting  to  reflect  that  at  least  100,000,000 
tons  of  coal  per  annum  is  being  lost  throughout  the  world  by 
lack  of  proper  methods  of  boiler  house  management. 


49 


PART  II. 

CRITICISMS  OF  EXISTING  CODES  AND  SUGGES- 
TIONS FOR  AN  IMPROVED  INTERNATIONAL 
CODE. 

i.  The  Necessity  of  Having  an  Entirely  Separate  Code 
for  Boiler  Plant  Testing. — It  is,  in  my  opinion,  a  fundamen- 
tal mistake  in  the  "Civils"  Code  to  lump  together  boiler 
plant  and  steam  engine  tests,  and  this  error  is  not  committed 
to  anything  like  the  same  extent  in  the  American  "  Mechani- 
cals "  Code,  which  is  divided  sharply  into  separate  test  codes 
for  boilers,  reciprocating  steam  engines,  steam  turbines,  pump- 
ing machinery,  compressors,  blowers  and  fans,  steam  power 
plants,  locomotives,  gas  producers,  gas  and  oil  engines,  and 
water-wheels.  The  arrangement  of  the  Civils  Code  is  appar- 
ently a  persistent  relic  of  the  days  of  over  100  years  ago, 
when  the  steam  engine  was  invented  and  developed,  and  when 
the  word  "  engine  "  meant  not  only  the  actual  steam  engine, 
but  the  boiler  and  accessories  as  well.  This  point  of  view 
may  have  had  some  justification  in,  say,  1822,  when  50  h.p. 
was  regarded  as  a  large  size  for  an  engine,  and  each  engine 
as  a  rule  had  its  own  small  separate  boiler.  In  1922,  how- 
ever, it  is  obviously  out-of-date,  because  of  the  size  and  com- 
plexity of  the  modern  steam  generation  plant,  and  because  of 
the  many  uses  of  the  steam,  not  only  for  engine  and  turbines 
of  greatly  different  sizes  and  efficiencies,  but  also  for  numerous 
other  processes,  such  as  warming  buildings,  drying  chambers, 
and  heating  liquids,  in  which  the  condensation  loss  in  the  pipe 
circuits  of  the  factory  alone  is  an  important  matter.  It  is  for 
this  same  reason  also  that  American  engineers  still  persist  in 

4 


50  BOILER  PLANT  TESTING 

talking  of  "  boiler  horse-power,"  an  unscientific  term  which 
has  died  out  in  Great  Britain  years  ago. 

The  only  practical  and  scientific  method  is  to  regard  the 
generation  of  steam  as  something  entirely  separate  and  inde- 
pendent from  the  utilisation  of*  steam,  whether  for  steam 
engines  or  for  any  other  process,  and  in  fact  one  of  the  reasons 
why  this  country  is  losing  20,000,000  tons  of  coal  per  annum 
on  steam  generation  is  because  this  very  point  is  not  under- 
stood. In  the  average  factory,  when  some  endeavour  is  made 
to  keep  a  record  of  the  figures  for  the  fuel  consumption,  such 
attempts  seldom  rise  above  the  conception  of  regarding  the 
boiler  and  power  plant  together  as  merely  one  item.  Thus, 
for  example,  a  paper-mill  expresses  the  figures  of  its  perform- 
ance as  so  many  tons  of  paper,  a  brewery  as  so  many  standard 
forty-gallon  barrels  of  beer,  a  flour-mill  as  so  many  sacks  of 
flour,  a  bleach  works  as  so  many  lumps  of  cloth,  all  per  ton 
of  coal. 

The  error  of  this  method  is  that  it  is  not  detailed  enough, 
and  there  is  not  only  entire  ignorance  as  to  whether  the  cause 
of  inefficiency  lies  in  the  generation  of  steam  at  the  boiler 
plant,  in  condensation  losses  in  the  steam  pipe  circuits,  or  in 
poor  engine  performance,  but  the  very  many  different  and 
important  functions  of  the  boiler  plant  are  carried  out  com- 
pletely in  the  dark. 

Yet  the  "  Civils "  Code  helps  to  perpetuate  this  funda- 
mental error  by  its  method  of  regarding  boiler  plant  and 
steam  engine  tests  as  something  almost  identical,  so  that  they 
can  be  included  in  one  Code. 

In  the  International  Code  I  suggest  that  boiler  plant  test- 
ing be  regarded  as  something  entirely  separate,  and  as  much 
independent  of  the  testing  of  steam  engines  as  it  is  of  oil  or 
gas  engines,  or  any  other  source  of  motive  power.  A  separate 
code  for  boiler  testing  also  means  greater  simplicity,  and 
would  be  a  great  help  in  convincing  every  one  that  efficient 
steam  generation  is  an  operation  of  vital  importance,  and 
worthy  of  the  most  careful  attention. 


CRITICISMS  OF  EXISTING  CODES  51 

2.  The  Object  of  Boiler  Plant  Testing.— The  "Civils" 
Code  gives  the  unfortunate  impression  that  boiler  plant  testing 
is  a  costly  and  troublesome  luxury  to  be  undertaken  only  at 
rare  intervals,  and,  secondly,  that  there  are  two  kinds  of  tests, 
namely,  to  "obtain  data  for  scientific  purposes,"  and  "com- 
mercial tests  "  to  ascertain  whether  the  guarantee  of  perform- 
ance given  by  the  maker  has  been  fulfilled.  It  also  speaks  of 
"  Comparative  trials  where  the  determination  of  efficiency  is 
not  the  main  object  ". 

The  four  separate  references  to  this  point  in  the  "  Civils  " 
Code  are  most  confusing,  and  are  given  below  (italics  my  own) : — 

(1)  Page  5.     "When  the  object  of  a  boiler  or  engine  trial 
is  to  obtain  data  for  scientific  purposes  the  losses  should  always 
be  measured,  because  they  afford  a  valuable  check  on  the  ac- 
curacy of  a  trial.     Such  measurements  consist  in  taking  the 
temperature  of  the  flue  gases  and  analysing  them,  weighing  the 
ash,  measuring  the  loss  of  heat  by  radiation,  etc.     Though  de- 
sirable, they  are  not  essential  in  a  large  majority  of  trials,  when 
those  observations  only  are  recorded  which  are  necessary  to 
ascertain  whether  the  guarantee  of  performance  given  by  the 
maker  has  been  fulfilled.     For  such  trials  a  shortened  tabular 
statement  has  been  provided  under  the  heading  '  Commercial 
Trials'1:' 

The  note  x  refers  the  reader  to  page  23,  which  reads  as 
follows,  at  the  bottom  of  the  page  : — 

(2)  Page  23.     "Notes:  (i)  The  lines  printed  in  italics  re- 
late to  data  which  may  be  omitted  where  a  shorter  form  of 
Report  for  general  purposes  is  desired  (see  Committee's  Report, 
P-  4>" 

On  turning  back  again  to  page  4  we  find : — 

(3)  Page  4.     "  As  regards  the  last  item,  the  original  forms 
intended  for  scientific  purposes^  in    which    it   is    necessary   to 
measure  the  losses,  have  been   retained  as  far  as  boilers  and 
reciprocating  engines  are  concerned,  but  abridged  forms  have 
also  been  drawn  up  for  more  general  use,  as  described  in  note 
i  on  page  23." 

Finally,  on  page  58  is  stated : — 

(4)  Page  58".     "  If  the  object  of  the  trial  is  to  ascertain,  for 


52  BOILER  PLANT  TESTING 

scientific  purposes,  the  rate  of  evaporation  for  a  constant  rate  of 
coal  consumption.   .  .  ." 

A  general  impression  also,  on  reading  through  the  "  Civils  " 
Code,  is  that  boiler  plant  testing  is  an  extremely  complicated 
and  difficult  operation,  which  involv.es  a  knowledge  of  chemistry 
and  mathematics  quite  beyond  the  ordinary  engineer,  and 
which  can  only  be  carried  out  by  the  University  graduate. 
These  ideas  are  quite  erroneous.  Boiler  plant  tests  must  be 
regarded  as  of  such  vital  importance  that  they  must  be  carried 
out  regularly  as  part  of  the  routine  of  the  daily  running  of  a 
boiler  plant,  and  there  is  nothing  mysterious  or  difficult  about 
them.  In  the  International  Code  I  would  suggest  one  standard 
code  for  all  boiler  tests,  and  to  do  away  with  any  idea  of  dis- 
tinction between"  Scientific"  and  "Commercial"  Tests,  which 
only  causes  confusion  and  which,  in  any  case,  is  wrong  in 
principle.  I  would  draw  up  the  Code  on  such  lines  that  the 
main  object  of  boiler  plant  testing  is  to  keep  boiler  plants  at 
the  maximum  efficiency  every  week,  all  the  year  round,  and 
such  a  Code  would  be  flexible  in  the  sense  that  it  would  in- 
clude all  special  tests,  such  as  the  investigation  of  a  particular 
quality  of  fuel,  of  any  plant,  machinery,  or  appliance  installed 
on  the  plant,  and  the  working  of  the  plant  under  different  con- 
ditions of  load. 

In  short,  boiler  plant  testing  must  be  regarded  as  a 
thoroughly  practical  proposition  which  is  necessary  for  the 
strictly  utilitarian  purpose  of  saving  money. 

3.  Duration  of  Test. — The  duration  of  the  test  is  a  matter 
of  the  greatest  importance  in  determining  the  true  performance 
of  a  boiler  plant,  and  the  "  Civils  "  Code  is  very  vague  on  this 
point.  All  the  definite  instructions  it  gives  are  as  follows 
(P.  9):- 

"The  approximate  duration  of  the  trial  should  be  fixed 
before  commencing  it,  and  should  be  a  multiple  of  the  period 
elapsing  between  the  times  of  cleaning  the  fires ;  it  should 
never  be  less  than  three  hours,  and  should  be  as  long  as  possible 
in  order  to  eliminate  error  in  the  measurement  of  the  thickness 
of  the  fuel." 


CRITICISMS  OF  EXISTING  CODES  53 

It  must  be  obvious  that  the  test  has  got  to  be  of  sufficient 
duration  to  allow  of  the  elimination  of  errors.  Thus,  I  pre- 
sume even  the  Civil  Engineers'  Committee  would  agree  that, 
for  example,  the  figures  of  a  test  of  one  hour's  duration  would 
be  worthless  as  a  true  indication  of  the  average  working  of  a 
boiler  plant.  To  allow  an  official  test  of  only  three  hours  is 
absolutely  ridiculous,  as  every  one  must  know  who  has  had 
much  practical  experience  of  boiler  plant  testing,  and  no  re- 
liance whatever  could  be  placed  upon  such  a  test. 

What  is  meant  by  the  statement  that  "  the  duration  of  the 
trial  should  be  fixed  before  commencing  it "  and  "  should  be  a 
multiple  of  the  period  elapsing  between  the  time  of  cleaning 
out,"  I  am  at  a  loss  to  understand. 

The  American  "  Mechanicals "  Code  is  infinitely  more 
sensible,  definite  and  practical  on  this  point,  as  follows : — 

Page  43.  "  44.  The  duration  of  tests  to  determine  the  effici- 
ency of  a  hand-fired  boiler  should  be  at  least  ten  consecutive 
hours.  In  case  the  rate  of  combustion  is  less  than  25  Ibs.  per 
sq.  ft.  of  grate  per  hour,  the  tests  should  be  continued  for  such 
a  time  as  may  be  required  to  burn  a  total  of  at  least  250  Ibs. 
of  coal  per  sq.  ft.  of  grate.  Tests  of  longer  duration  than  ten 
hours  are  advisable  in  order  to  obtain  greater  accuracy. 

"45.  In  the  case  of  a  boiler  using  a  mechanical  stoker,  the 
duration,  where  practicable,  should  be  at  least  twenty-four 
hours.  If  the  stoker  is  of  a  type  that  permits  the  quantity  and 
condition  of  the  fuel  bed  at  beginning  and  end  of  the  test  to 
be  accurately  estimated,  the  duration  may  be  reduced  to  ten 
hours,  or  such  time  as  may  be  required  to  burn  the  above  noted 
total  of  250  Ibs.  per  sq.  ft. 

"  In  commercial  tests  where  the  service  requires  continu- 
ous operation  night  and  day,  with  frequent  shifts  of  firemen, 
the  duration  of  the  test,  whether  the  boilers  are  hand-fired  or 
stoker-fired,  should  be  at  least  twenty-four  hours.  Likewise 
in  commercial  tests,  either  of  a  single  boiler  or  of  a  plant  of 
several  boilers,  which  operate  regularly  a  certain  number  of 
hours  and  during  the  balance  of  the  day  the  fires  are  banked, 
the  duration  should  not  be  less  than  twenty-four  hours. 

"  The  duration  of  tests  to  determine  the  maximum 
evaporative  capacity  of  a  boiler,  without  determining  the 
efficiency,  should  not  be  less  than  three  hours." 


54  BOILER  PLANT  TESTING 

It  will  be  noted  that  the  American  Code  insists  on  at  least 
ten  consecutive  hours,  and  that  the  three  hours  allowed  by 
the  "  Civils "  Code  for  the  complete  test  is  in  the  American 
Code  only  allowed  for  the  comparatively  unimportant  opera- 
tion of  determining  the  maximum'evaporative  capacity  of  the 
plant,  quite  irrespective  of  the  efficiency. 

Surely  the  common-sense  guide  to  the  duration  of  the  test 
is  the  actual  practical  working  conditions  of  the  given  boiler 
plant.  If,  for  example,  the  boiler  plant  starts  up  at  8  a.m., 
runs  full  output  until  12  midday,  partially  shuts  down  for  the 
dinner  hour  until  I  o'clock,  and  then  runs  full  output  again  to 
5  o'clock,  the  only  proper  course  is  to  run  the  test  right  through 
for  nine  hours,  that  is  from  8  a.m.  to  5  p.m.,  including  the 
partial  stop  in  the  dinner  hour.  In  a  colliery,  for  example,  or 
under  colliery  conditions  on  an  experimental  plant,  the  maxi- 
mum "winding  period"  may  be  from  6. am.  to  2  p.m.,  in 
which  case  the  test  would  be  carried  out  for  this  period. 

Certain  industries,  such  as  flour-mills  and  paper-mills,  as 
a  rule,  run  right  through  twenty-four  hours  a  day  on  steady 
load  for  six  days,  in  which  case,  of  course,  the  test  can  be 
carried  out  at  any  time. 

I  would  propose  that  in  the  International  Code  no  test 
should  be  regarded  as  official  if  of  less  duration  than  eight 
hours,  and  in  every  case  longer  than  this,  or  the  full  working 
day  or  shift,  is  much  preferable.  In  the  few  cases  where  the 
complete  working  day  or  shift  is  less  than  eight  hours,  I  would 
allow  the  lesser  time,  but  would  attach  little  importance  as  a 
rule  to  any  test  of  less  than  six  hours'  duration. 

It  would  not  be  possible  to  include  the  American  figures 
of  ten  hours  and  twenty-four  hours  in  an  International  Code, 
because,  for  example,  in  this  country  the  average  working  day 
is  now  only  eight  hours. 

On  this  point  of  the  duration  of  the  test  a  second  very 
serious  matter  for  criticism,  in  both  the  "  Civils "  Code  and 
the  American  "  Mechanicals  "  Code,  is  the  total  omission  of  all 
reference  to  the  figures  for  the  performance  of  the  boiler  plant 


CRITICISMS  OF  EXISTING  CODES  55 

when  starting  and  stopping,  when  banked  up,  and  on  light 
load  at  night*  and  during  the  week-end.  Most  boiler  plants  do 
not  suddenly  start  up  at  full  load,  run  for  a  test  period,  and 
then  suddenly  shut  down  again.  The  usual  practice  is  to  run 
on  intermittent  loads  during  the  night,  for  keeping  buildings 
warm  and  perhaps  working  the  factory  at  much  reduced  load ; 
and  also  for  the  boiler  plant  to  remain  banked  up  under 
pressure  during  the  week-end,  if  only  to  be  able  to  work  the 
pumps  in  case  of  fire. 

Speaking  in  averages,  anything  from  10  to  30  per  cent,  of 
the  annual  coal  bill  is  usually  absorbed  in  this  way,  and  a  test 
carried  out  in  the  spirit  of  both  the  Codes  only  applies  there- 
fore to  the  70  to  79  per  cent,  of  the  coal  burnt  during  ordinary 
working  hours. 

I  found  out  very  soon,  by  practical  experience,  that  it  is 
necessary  to  carry  out  a  long  check  test  to  include  the  essential 
elements  of  the  day's  test,  namely,  the  amount  of  water 
evaporated  and  coal  burnt,  together  with  the  heating  value  of 
the  coal,  and  consequently  out  of  the  400  tests,  365  tests  have 
a  long  check  test  of  one  complete  week  in  addition.  In  the 
International  Code,  therefore,  I  would  suggest  a  long  check 
te^t  of  a  complete  week  of  1 68  hours,  that  is,  including  the 
full  week-end,  and  the  combination  of  the  two  tests,  namely,  a 
day  test  of  not  less  than  eight  hours,  and  a  full  week's  test, 
will  give,  in  my  opinion,  a  much  more  satisfactory  test  of  a 
boiler  plant  both  from  a  practical  as  well  as  from  an  academic 
and  scientific  point  of  view. 

In  the  400  tests,  thirty-five  plants  were  tested  during  the 
day  only,  either  because  it  was  impossible  to  carry  out  a  week's 
check  test  without  a  great  deal  of  trouble,  or  because  of  the 
express  wish  of  the  client.  In  the  remaining  365  tests, 
185  plants  gave  a  slightly  inferior  result  as  compared  with 
the  day's  test,  and  1 80  tests  showed  a  somewhat  better  result. 
There  is  always  some  loss  by  cooling  during  the  week-end, 
but  this  is  often  counter-balanced  by  the  fact  that  a  boiler 


56  BOILER  PLANT  TESTING 

plant  may  have  been  forced  during  the  day,  so  that  the 
efficiency  is  less  than  at  night  when  on  easy  load. 

4.  Sampling  and  Analysis  of  the  Fuel. — Both  Codes 
give,  on  the  whole,  very  clear  instructions  as  to  the  sampling 
of  the  fuel,  and  the  necessity  <«f  taking  proper  average 
samples.  There  is  no  doubt  that  many  boiler  trials  are 
rendered  of  little  value  through  defective  sampling,  and  it  is 
somewhat  difficult  to  lay  down  definite  rules  for  this  operation, 
which  is,  after  all,  a  matter  of  common  sense.  I  think,  how- 
ever, the  instructions  in  the  Codes  would  be  improved  if  they 
insisted  that  two  entirely  independent  samples  of  the  fuel  are 
taken  during  the  trial.  Thus,  if  samples  are  taken  from  each 
barrow,  or  bag,  or,  say,  at  intervals  of  half  an  hour  from  rail- 
way waggons  or  overhead  bunkers,  it  is  better  to  keep  two 
separate  samples  (A  and  B)  and  to  place  them  separately  in 
two  receptacles  (A  and  B)  during  the  trial.  At  the  end  of  the 
trial  the  two  large  samples  are  then  mixed,  broken  up,  quartered, 
etc.,  and  small  portions  sent  for  analysis  in  separate  sealed 
tins  (A  and  B).  These  are  then  analysed  separately  and 
the  results  given  are  an  average  of  the  two  separate  analyses. 
I  have  found  this  in  practice  a  very  satisfactory  method,  and 
would  suggest,  therefore,  that  this  be  embodied  in  the  Inter- 
national Code,  with  the  proviso  that  it  is  of  course  impossible 
to  take  too  many  samples,  and  these  instructions  be  regarded 
as  the  minimum  requirements. 

On  the  question  of  the  analysis  of  the  fuel,  and  the  gross 
and  net  heating  value,  neither  Code  is  very  lucid.  The 
"  Civils  "  Code  decides  that  the  efficiency  calculations  shall  be 
based  on  a  calculated  lower  or  net  heating  value,  whilst  the 
American  "  Mechanicals "  Code  takes  the  simple  or  gross 
heating  value  of  the  dried  coal  as  determined  in  the  oxygen 
bomb  calorimeter. 

It  is  agreed  in  the  first  place  by  all  concerned  that  the 
calorimeter  to  be  used  for  the  determination  of  the  gross 
heating  value  of  a  fuel  shall  be  of  the  oxygen  bomb  type,  in 
which  a  weighed  amount  of  fuel  is  burnt  in  a  known  weight 


CRITICISMS  OF  EXISTING  CODES  57 

of  water  at  a  known  temperature.  The  rise  in  temperature  of 
the  surrounding  water,  as  recorded  by  a  delicate  thermometer, 
will  then  give  an  absolutely  accurate  measurement  of  the 
amount  of  heat  in  the  fuel,  since  the  combustion  is  complete, 
as  it  is  in  high  pressure  oxygen,  and  no  heat  can  be  lost, 
because  it  takes  place  in  a  sealed  bomb  under  the  water. 

The  "Civils"  Code  mentions  on  page  37,  in  the  In- 
troduction, Appendix  I.,  under  the  "  List  of  Apparatus 
required  for  a  Boiler  Test,"  item  No.  13,  "A  Barms  or  other 
Calorimeter* '. 

So  far  as  I  am  aware  no  such  instrument  has  ever  been  in 
general  use  in  Great  Britain,  the  three  best-known  makes  of 
oxygen  bomb  calorimeter  in  this  country  being  the  "  Mahier- 
Donkin,"  the  "  Mahler-Cooke  "  and  the  "  Berthelot-Mahler," 
all  of  which  are  most  efficient  instruments. 

The  "  Civils  "  Code  would  seem  to  imply  that  it  regards 
the  "  Barrus  "  calorimeter  (apparently  an  American  instrument) 
as  the  best,  but  I  would  suggest  that  in  the  International  Code 
any  approved  make  of  oxygen  bomb  calorimeter  would  be 
allowed.  The  American  "Mechanicals"  Code  does  not 
mention  the  Barrus  calorimeter  but  recommends  (p.  19)  the 
Mahler  type. 

The  heating  value  so  determined  in  a  bomb  calorimeter  is 
termed  the  "  gross "  or  higher  heating  value.  This  value, 
however,  is  not  the  same  as  the  actual  heating  value  available 
for  a  boiler  from  the  combustion  of  the  fuel  in  the  fire,  firstly 
because  of  the  natural  moisture,  and,  secondly,  because  of  the 
percentage  of  hydrogen,  in  the  coal.  All  coal  contains  such 
natural  moisture,  which  may  vary  from,  say,  2  to  8  per  cent., 
and  if  the  coal  is  completely  dried,  it  at  once  re-absorbs  this 
moisture  from  the  air.  Further,  coal  delivered  to  a  boiler 
plant  may  contain  up  to  25  per  cent,  moisture  if  it  has  been 
washed,  or  exposed  to  the  weather.  Also  dry  coal  contains 
hydrogen  as  one  of  its  normal  constituents,  the  amount 
usually  varying  from  2  to  4  per  cent. 

J.  S.  S.  Brame  ("Fuel,  Solid,  Liquid  and  Gaseous,"  1919) 


BOILER  PLANT  TESTING 


gives  the  ultimate  composition  of  various  coals  as   follows, 
that  is,  without  taking  into  account  ash  and  moisture : — 


Carbon. 

Hydrogen. 

Oxygen  and 
Nitrogen. 

Splint  coal  (Fife)      . 

82'0 

5-00 

1  2  '80 

Gas  coal  (Durham)  . 

85-0 

5-50 

8-20 

Coking  coal      .         .                           . 

87-3 

5-05, 

6'QO 

Smokeless  coal  (Welsh) 

91*3 

4*°5 

3-90 

Anthracite  (Scotch) 

QI-I 

3-50 

4-65 

(Welsh) 

QI'O 

3-90 

4-28 

During  the  combustion  of  coal  the  hydrogen  burns  to 
water,  and  consequently  in  a  bomb  calorimeter  the  natural 
moisture  of  the  coal,  and  the  moisture  formed  by  the  burning 
of  the  hydrogen,  is  first  volatilised  to  steam,  which  is  enclosed 
in  the  bomb  and  cannot  escape,  and  then,  because  of  the  cool- 
ing water  outside,  is  condensed  to  water  again  inside  the  bomb, 
and  gives  up  all  its  latent  heat,  which  is  therefore  included  in 
the  gross  heating  value  of  the  coal. 

For  example,  take  a  coal  of  1 1,500  B.Th.U.  gross  heating 
value  as  determined  in  the  bomb  calorimeter,  and  having  5 
per  cent,  of  natural  moisture,  and  4*0  per  cent,  of  hydrogen, 
calculated  to  the  coal  as  fired,  and  exclusive  of  the  hydrogen 
in  the  moisture. 

If  the  water  in  the  calorimeter  jacket  outside  the  bomb  is 
60°  F.,  so  that  the  condensed  water  from  the  combustion  of 
the  coal  inside  the  bomb  will  also  be  cooled  to  60°  F.,  the  heat 
given  up  in  the  bomb  by  I  Ib.  of  water,  in  condensing  from 
steam,  would  be  970*7  B.Th.U.,  the  latent  heat  in  I  Ib.  of 
steam,  and  roughly  152*0  B.Th.U.  in  cooling  from  water  at 
212°  to  60°  F.,  that  is,  a  total  of  11227  B.Th.U. 

Since  the  percentage  of  moisture  in  the  coal  is  5,  in  I  Ib. 
of  coal  which  has  a  gross  heating  value  as  determined  by  the 
bomb  calorimeter  of  11,500  B.Th.U.  per  Ib.,  56'!  B.Th.U.  (5 
per  cent  of  1122*7)  will  be  really  due  to  the  natural  moisture 
of  the  coal,  being  retained  in  the  coal  and  cooled  to  60°  F. 


CRITICISMS  OF  EXISTING  CODES  59 

If  we  assume,  however,  that  in  a  boiler  furnace  all  the 
water  in  the  coal  is  vaporised,  and  passes  right  out  of  the 
plant  to  the  chimney  base  as  steam  in  the  flue  gases,  and  the 
temperature  of  the  coal  when  thrown  into  the  fire  is  60°  F. 
(and  therefore  the  5  per  cent,  water  in  the  coal  is  also  60°  F.) 
and  the  temperature  of  the  exit  gases  is,  say,  350°  F.,  the  loss 
of  heat  per  Ib.  of  water  in  the  coal  will  be  154*6  units,  to  heat 
the  water  in  the  coal  from  60°  to  212°  F.  9707  units  to 
convert  the  water  at  212°  F.  to  steam  at  212°  F.  (latent  heat), 
and  62  units  to  heat  the  steam  to  350°  F.  (the  average  tem- 
perature of  the  exit  gases),  taking  the  specific  heat  of  steam  at 
atmospheric  pressure  as  0-45,  making  thus  a  total  of  1187*3 
B.Th.U. 

Since  the  percentage  of  water  in  the  coal  is  5,  the  heat 
lost  per  Ib.  of  coal  is  therefore  59*36  (5  per  cent,  of  1187*3). 
The  real  net  heating  value  of  the  coal,  for  these  particular 
conditions,  taking  into  account  the  moisture  only,  is  therefore 
11,500  -  59*36  =  11,440-6  B.Th.U. 

In  the  same  way  the  4  per  cent,  of  hydrogen  in  the  coal 
burns  and  forms  an  amount  of  water  equivalent  to  35*76  per 
cent,  of  the  weight  of  the  coal  (i  part  by  weight  of  hydrogen 
unites  with  7-94  parts  of  oxygen  to  give  8  -94  parts  of  water), 
and,  as  before,  this  escapes  up  the  chimney  as  steam  at 
350°  F.  The  heat  lost  is  therefore  424*6  B.Th.U.  (35*76  per 
cent,  of  1187-3). 

Although  the  gross  heating  value  by  means  of  a  bomb 
calorimeter  of  such  a  coal  is  11,500  B.Th.U.,  the  actual 
net  heating  value  under  the  given  practical  conditions  will 
only  be  11,500  -  59*3  -  424-6,  that  is,  1 1,016-2  B.Th.U., 
certainly  a  very  serious  difference. 

It  is  obvious,  however,  that  in  arriving  at  a  lower  heating 
value  of  the  coal,  it  is  not  possible  to  include  the  various  tem- 
peratures of  the  exit  gases  on  different  boiler  plants.  If  this 
was  done,  the  higher  the  exit  gases  (and  therefore  the  more  in- 
efficient the  plant)  the  lower  would  be  the  calculated  lower 
heating  value  of  the  coal,  which  would  favour  the  plant  with 


60  BOILER  PLANT  TESTING 

the  highest  exit  temperature,  and,  further,  the  lower  heating 
value  of  any  fuel  could  not  be  given  until  the  temperature  of 
the  exit  gases  of  the  corresponding  boiler  plant  was  known. 
The  only  possible  way,  therefore,  is  to  assume  that  the  tem- 
perature of  the  coal  is  60°  F.  aad  to  deduct  for  each  I  Ib.  of 
water  in  the  coal,  say,  154*6  B.Th.U.  to  heat  the  water  in  the 
fires  from  60°  to  212°  F.  and  9707  B.Th.U.  to  convert  I  Ib.  of 
water  at  212°  F.  into  steam  at  212°  F.,  that  is,  a  total  of, 
1125*3  B.Th.U.  The  reason  for  taking  212°  F.  is  that  this  is 
in  practice  the  theoretically  perfect  exit  temperature  of  a  boiler 
plant,  because  if  the  temperature  was  211°  F.  all  the  water  in 
the  flue  gases,  sometimes  as  much  as  50  per  cent,  of  the 
weight  of  the  coal,  would  condense  in  the  flues  and  render  the 
plant  unworkable.  There  is  a  further  complication  with  regard 
to  this  question  of  the  higher  and  lower  heating  value.  It 
does  not  necessarily  follow  that  all  the  water  from  the  coal 
actually  does  escape  to  the  chimney  as  steam,  carrying  all  the 
latent  and  other  heat.  It  is  true  that  the  temperature  in  the 
chimney  base  is  hardly  ever  less  than  300°  to  350°  F.  and  cer- 
tainly nothing  approaching  212°  F.,  so  that  theoretically  all 
the  moisture  should  pass  away  as  steam,  but  it  is  almost 
certain  that  in  exposed  portions  of  the  plant,  such  as  the 
brickwork  of  the  economiser,  underneath  the  front  of  the 
boiler  where  cold  air  is  almost  always  entering,  and  so  on, 
some  portion  of  the  moisture  is  condensed  locally.  We  know, 
for  example,  that  this  is  often  the  case  with  the  economiser 
pipes,  giving  what  is  known  as  "  sweating,"  which  causes  cor- 
rosion. Whenever  this  local  condensation  takes  place,  the 
latent  heat  is  given  up  to  the  plant,  and  does  not  pass  away. 
If  this  is  granted,  it  is  not  absolutely  correct  to  calculate  the 
net  heating  value  of  the  fuel  as  is  done  in  the  "  Civils  "  Code, 
since  we  have  an  indeterminate  and  unknown  factor  which 
would  make  the  real  practical  heating  value  of  the  coal  some- 
where between  the  ordinary  gross  (higher)  and  net  (lower) 
figures,  although  of  course  the  usual  calculated  net  figure 
would  be  much  more  accurate  than  the  gross  figure. 


CRITICISMS  OF  EXISTING  CODES  61 

The  chief  objection,  however,  to  the  method  of  using  the 
calculated  net  or  lower  heating  value  is  the  necessity  of 
carrying  out  every  time  the  complicated  and  troublesome 
organic  analysis  of  the  percentage  of  hydrogen  in  the  coal. 

As  already  emphasised,  we  have  to  look  at  this  boiler 
plant  testing  from  a  practical  point  of  view,  as  something 
which  must  be  done  regularly  as  part  of  the  routine  of  the 
plant. 

I  would  suggest,  therefore,  in  the  International  Code  to 
abandon  the  idea  of  using  the  calculated  net  or  lower  heating 
value,  and  to  substitute  for  it  the  higher  heating  value  as  ob- 
tained in  the  oxygen  bomb  calorimeter  from  the  dried  sample 
of  fuel,  and  then  calculated  back  to  the  percentage  of  moisture. 
That  is  to  say,  the  percentage  of  moisture  in  the  coal  would 
be  first  determined,  and  the  heating  value  of  the  dried  coal 
obtained  by  means  of  the  bomb  calorimeter. 

Thus,  to  take  an  actual  case,  a  given  water-tube  boiler 
evaporated  310,000  Ibs.  of  water  in  S'OO  hours,  the  temperature 
of  the  water  being  110°  F.  before  the  economisers  and  275-0° 
F.  after.  The  boiler  pressure  was  200  Ibs.  (gauge)  and  the 
superheat  temperature  645°  F.  (specific  heat  calculated  as 
0-541).  The  amount  of  coal  burnt  was  53,850  Ibs.  The 
coal  on  analysis  was  found  to  contain  11*58  per  cent,  of 
moisture,  and  the  actual  gross  heating  value  of  the  dried  coal 
was  10,823  B.Th.U.  per  lb.,  whilst  the  percentage  of  hydrogen 
in  the  dried  coal  was  375  (determined  specially  for  this  ex- 
ample). The  corresponding  simple  calculated  gross  heating 
value  for  the  coal  as  fired  would  be  9570  B.Th.U.  (10,823  in 
the  dry  and  9570  in  the  damp,  with  11*58  per  cent,  of  water). 
The  calculated  lower  heating  value,  according  to  the  method  I 
should  prcpose,  would  be  94397  B.Th.U.,  that  is,  the  loss  by 
heating  11*58  per  cent,  of  water  in  the  coal  from  60°  to  212° 

F.  (=  17-90  B.Th.U.  being,  as  already  seen,  -^ — -    *54    ) 

I OO  / 

and  converting  it  into  steam  at  212°  F.  (  =  1 12-41  being,  as 


62  BOILER  PLANT  TESTING 

before,  11-58  x      ^  ),  making  a  total  of  130-3  B.Th.U.  to  be 
i  oo  / 

deducted  (9570  -  130-3  =  94397).  The  calculated  lower 
heating  value,  including  the  organic  hydrogen,  would  be 
9106-9  B.Th.U.  The  percentage  of  organic  hydrogen  in  the 
dried  coal  being  3-75,  this  in  the'- damp  coal  (11-58  per  cent, 
water)  corresponds  to  3-32  per  cent.  As  already  seen,  3-32 
per  cent,  hydrogen  produces  3*32  x  8-94  =  29-68  water,  and 
this  on  heating  from  60°  to  212°  F.  and  converted  to  steam 
at  212°  F.  will  absorb  333-9  B.Th.U.,  so  that,  added  to  130-3 
B.Th.U.,  due  to  the  moisture,  the  total  deduction  will  be 
464-2  B.Th.U.,  that  is,  9571  -  464-2  =  9105*8  B.Th.U. 
Further,  the  gross  heating  value,  as  determined  by  the  bomb 
calorimeter,  of  the  damp  coal  as  fired  was  found  to  be  9521 
B.Th.U.  We  have  therefore  three  distinct  heating  values 
possible  for  this  coal,  namely,  9521  B.Th.U.,  the  gross  value 
in  the  bomb  as  fired,  9439 "7,  the  calculated  net  value,  not 
including  the  organic  hydrogen  but  including  the  water  and 
assuming  an  exit  temperature  of  212°  F.  on  the  plant,  and 
9105-8,  including  both  the  water  and  the  hydrogen,  and 
assuming  as  before  an  exit  temperature  of  212°  F. 

The  objection  to  the  method  suggested,  that  is,  ignoring 
the  organic  hydrogen,  is  of  course  that  this  organic  hydrogen 
content  may  vary  from  almost  zero  in  the  case  of  coke,  up  to 
as  high  as  4  to  5  per  cent,  in  very  bituminous  coal.  I  have 
drawn  a  curve  (Fig.  i)  showing  the  number  of  B.Th.U.  to  be 
deducted  for  any  corresponding  percentage  of  hydrogen,  and 
as  seen,  the  figure  is  practically  100  B.Th.U.  for  every  I'O  per 
cent,  organic  hydrogen  in  the  coal.  By  the  method  suggested, 
therefore,  the  larger  the  percentage  of  hydrogen  in  a  coal,  the 
greater  is  the  error  in  favour  of  the  boiler  plant,  so  that  with 
any  given  plant  the  best  calculated  results  would  be  shown  by 
using  a  bituminous  coal,  and  the  worst  by  using  anthracite, 
and  above  all,  coke.  We  are  faced,  however,  with  the  difficulty 
that  to  obtain  the  greatest  accuracy  on  this  point  a  greatly 
increased  amount  of  trouble  is  necessary,  and,  in  my  opinion, 
this  is  not  justified  from  a  practical  point  of  view. 


CRITICISMS  OF  EXISTING  CODES 


Another  suggestion,  however,  would  be  to  take  the 
percentage  of  hydrogen  in  all  coals  as  either  the  arbitrary 
figure  of  3  per  cent.,  or  perhaps  0-03  per  cent,  of  the  heating 
value  as  determined  in  the  dried  coal,  and  calculated  for 
moisture  only.  In  the  former  case  300  JB.Th.U.  would  then 
be  subtracted,  and  in  the  latter  case,  with  a  heating  value  of 


8 


Of 

HYDROGEN 


100 


Zoo 


3oo 


4oo 


Soo 


fcoo 


700 


FIG.  i.— Curve  showing   the  B.Th.Us.  to  be   deducted  for   a   corresponding 
percentage  of  hydrogen  calculated  in  the  coal  as  fired. 

94397  B.Th.U.  the  figure  would  be  94397  x  0*03  =  283-19. 
This,  subtracted  from  94397,  would  give  9156-5  as  the  final 
heating  value.  Some  such  arrangement  would  reduce  the 
practical  error  to  a  negligible  quantity,  and  would  probably 
be  as  accurate  as  the  present  complicated  method  involving 
the  determination  of  hydrogen. 


BOILER  PLANT  TESTING 


In  order  to  show  the  different  efficiency  figures  obtained 
by  these  various  heating  values,  the  actual  figures  of  the  test 
results  already  given,  work  out  as  follows  : — 


B.Th.U.  Gross 
Actually  in  the 
Coal  as  Fired, 
9521  B.Th.U. 

y 

B.Th.U.  in  Dry 
Coal  and  Cal- 
culated for 
Moisture," 
94397  B.Th.U. 

B.Th.U.  in  Dry 
Coal  and  Cal- 
culated for 
Moisture  and 
Organic 
Hydrogen. 
9105-8  B.Th.U. 

B.Th.U.  in  Dry 
Coal  and  Cal- 
culated for 
Moisture  and 
0-03  x  Heat 
Value  in  Lieu 
of  Hydrogen, 
9166-5  B.Th.U. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Net  working  efficiency  of  plant 

after    deducting    1*5    per 

cent,  auxiliary  steam  used 

on  the  plant 

73-10 

7576 

78-54 

78-12 

Heat  absorbed  by  the  boiler     . 

5770 

58-20 

6034 

60*02 

Heat  absorbed  by  the   econo- 

miser        .... 

IO'I5 

10-23 

10-60 

10-55 

Heat  absorbed  by  the   super- 

heater      .... 

8'39 

8-48 

8-80 

875 

There  is,  therefore,  a  difference  of  about  2-J-  to  3  per  cent, 
in  the  efficiency,  according  as  to  whether  organic  hydrogen  is 
included  or  not,  always  remembering  that  in  the  latter  case 
we  assume  the  coal  to  be  60°  F.  and  all  the  moisture  from  the 
coal  escapes  from  the  boiler  plant  as  steam  at  212°  F. 

In  view  of  the  great  confusion  existing  on  this  point,  and 
the  trouble  necessary  to  determine  the  organic  hydrogen,  the 
400  tests  have,  as  already  stated,  been  calculated  according  to 
the  more  usual  practice  on  the  gross  heating  value  of  the  fuels 
as  determined  by  the  bomb  calorimeter.  In  proposing  now 
to  use  a  calculated  lower  figure,  ignoring  the  organic  hydrogen, 
it  has  always  to  be  remembered  that  any  International  Code 
gives  the  minimum  data  necessary.  There  is  nothing  to 
prevent  any  given  test,  by  arrangement,  including  the  organic 
hydrogen  as  supplementary. 

5.  Flue  Gas  Analysis. — I  am  of  the  opinion  that  the 
methods  suggested  by  both  Codes  for  flue  gas  analysis  are 
out-of-date.  They  do  not  explain  at  all  clearly  what  is  the 
object  of  flue  gas  analysis,  and  confine  their  attention  almost 


CRITICISMS  OF  EXISTING  CODES  65 

entirely  to  the  old-fashioned  method  of  hand  analysis,  and 
even  then  the  methods  described  are  often  not  practical. 

With  regard  to  the  theory  of  gas  analysis  :  Air  contains 
21  per  cent  of  oxygen  by  volume,  and  if  coal  (or  other  fuel) 
was  pure  carbon,  and  just  the  right  amount  of  air  was  used, 
then  the  flue  gases,  that  is,  the  air  after  passing  through  the 
fires,  would  contain  2 1  per  cent,  carbon  dioxide  (CO2).  Since 
coal  is  not  pure  carbon,  and,  as  fired,  may  contain  only 
from  60  to  90  per  cent,  whilst  at  the  same  time  hydrogen  is 
present  to  the  extent  of  say  2  to  4  per  cent,  which  burns  to 
water,  it  is  obvious  that  21  per  cent  CO2  cannot  be  obtained, 
even  if  the  combustion  is  perfect  With  anthracite  or  coke, 
say  1 8  to  IQ-J-  per  cent  can  be  regarded  as  a  theoretical  figure, 
and  for  ordinary  semi-bituminous  steam  coal  say  17  to  1 8 
per  cent  If  less  than  these  figures  for  CO2  are  obtained,  it 
may  indicate  that  excess  air  is  passing  through  the  furnace, 
that  is  to  say,  there  is  a  drop  in  efficiency  due  to  this  excess 
air  carrying  heat  away  from  the  plant.  We  have  also  to 
consider  the  case  when  less  air  than  the  theoretical  is  passing 
through  the  fires.  In  this  case  part  of  the  carbon  of  the  fuel 
only  burns  to  CO  (carbon  monoxide)  because  there  is  not 
sufficient  oxygen  to  complete  the  combustion  to  CO2,  and  the 
flue  gases  contain  free  CO  along  with  a  high  percentage  of 
CO2.  This  represents  a  very  serious  loss  in  efficiency  because 
CO  is  an  inflammable  gas,  and  I  Ib.  of  carbon  burnt  to  CO 
only  gives  4400  B.Th.U.  instead  of  14,544  B.Th.U.,  when 
properly  burnt  to  CO2. 

Also,  it  is  possible  to  have  CO,  CO2  and  excess  air  present 
in  a  flue  gas  at  the  same  time,  because  in  one  part  of  the 
furnace  there  may  be  an  excess  of  air  and  in  another  part  a 
deficiency.  Generally,  however,  a  low  CO2  percentage  means 
no  CO,  and  CO  is  usually  present  to  an  appreciable  amount 
only  when  there  is  a  high  CO2  percentage.  It  may  be  added 
that  flue  gases  may  contain  also  minute  amounts  of  methane 
(CH4),  hydrogen  (H2)  and  sulphur  dioxide  (SO2),  but  these  are 
of  no  practical  importance. 

5 


66  BOILER  PLANT  TESTING 

It  will  be  obvious,  therefore,  that  the  analysis  of  the  flue 
gas  is  a  vital  part,  not  only  of  the  testing  of  a  boiler  plant, 
but  also  of  its  daily  running  as  well,  and  if  the  flue  gases  are 
not  analysed  regularly  it  is  not  possible  to  keep  the  plant  up 
to  the  highest  efficiency  by  controlling  the  firing. 

The  principle  of  flue  gas  analysis  is  to  take  a  measured 
volume  of  the  gas,  say  100  c.c.,  at  normal  temperature  and 
pressure,  and  to  pass  it  through  20  to  25  per  cent,  caustic  potash 
solution.  This  absorbs  the  CO2  (and  any  traces  of  sulphur  di- 
oxide or  other  acid  gases),  and  the  reduction  in  volume  gives 
the  percentage  of  CO2,  i.e.,  if  90  c.c.  of  gas  is  left,  there  is  10 
per  cent,  of  CO2.  The  90  c.c.  of  gas  is  then  passed  through  7| 
per  cent,  pyrogallic  acid  in  2  5  per  cent,  caustic  potash  solution 
(or  over  phosphorus),  which  absorbs  the  oxygen,  and  after  the 
further  reduction  in  volume  has  been  read  off,  the  remaining 
gas  is  passed  into  a  solution  of  12  per  cent,  cuprous  chloride 
in  25  per  cent,  hydrochloric  acid,  which  absorbs  the  CO. 

Such  an  analysis  is  carried  out  by  hand  in  an  "  Orsat"  or 
similar  apparatus,  but  the  process  is  very  tedious  and  takes 
twenty  to  thirty  minutes  for  one  analysis,  and  it  is  not  sur- 
prising, therefore,  that  many  attempts  have  been  made  to 
invent  a  continuous  gas  analysing  machine.  The  ideal  for 
boiler  testing  and  control  would  be  a  machine  that  would  give 
a  record  every  few  minutes  of  the  percentage  of  CO2  and  CO 
and  other  escaping  inflammable  gas.  Only  within  the  last 
few  months  has  such  a  machine  been  perfected,  after  years  of 
experimenting,  by  the  Svenska  Aktiebolaget  "Mono"  Co.  of 
Stockholm,  and  is  now  on  the  American  and  British  markets 
under  the  name  of  the  "  Duplex  Mono  "  (automatic  gas  analys- 
ing machine). 

This  machine  is  a  revolution  in  flue  gas  analysis,  as  it  takes 
automatically  a  sample  of  flue  gas  at  the  rate  of  twenty  times 
an  hour,  determines  the  percentage  of  CO2  in  every  alternate 
sample  and  writes  down  the  result  on  a  chart  together  with  the 
time  of  the  analysis,  and  in  the  other  alternate  sample  burns  first 
in  the  machine  the  unburnt  gas  to  CO2,  and  then  determines  the 


FIG.  2. — Record  with  "  Duplex  Mono"  ordinary  working,  showing  varying  CO2, 
and  much  CO  and  unburnt  gases  at  periods  commencing  B  and  C. 


FIG.  3. — Record  with  "Duplex  Mono"  showing  ideal  working  with  high  CO2 
and  no  CO,  except  at  one  short  half-hour  period. 

[To  face  p.  67. 


CRITICISMS  OF  EXISTING  CODES  67 

CO2,  the  increase  being  due  to  unburnt  gas.  It  is  difficult  to 
explain  the  operation  of  the  "  Duplex  Mono  "  in  a  few  words, 
but  the  machine  works  by  the  rise  and  fall  of  mercury  driven 
by  water  power  or  compressed  air,  and  the  samples  of  flue  gas 
are  automatically  and  alternately  diverted  direct  to  the  caustic 
potash  solution  for  the  determination  of  CO2  and  then  through 
a  small  electric  heated  furnace  containing  copper  oxide  on  the 
top  of  the  machine  in  which  all  unburnt  gas  is  consumed,  and 
afterwards  to  the  caustic  potash.  Specimen  charts  are  shown 
in  Figs.  2  and  3.  In  Fig.  2,  following  the  points  B  and  C,  there 
is  a  large  amount  of  unburnt  gas,  since  the  records  of  each 
alternate  analysis  are  far  apart.  If  one  series  of  samples 
shows  about  10  per  cent.  CO2  and  the  alternate  series  12  per 
cent,  it  is  a  clear  indication  of  unburnt  gas,  since  the  CO  has 
been  burnt  to  CO2  in  the  electric  furnace  and  increased  the 
percentage  of  CO2.  The  ideal  is  shown  in  Fig.  3  where 
the  average  CO2  for  many  hours  is  about  1 1  per  cent.,  with 
only  a  little  CO  for  half  an  hour. 

The  "  Duplex  Mono"  is  illustrated  in  Figs.  4,  5,  6,  and  a 
previous  machine  for  the  determination  of  CO  and  unburnt 
gases  only  in  Fig.  7.  The  original  "Mono"  CO2  Recorder 
only  is  identical  with  the  "Duplex  Mono"  but  without  the 
mechanism  for  CO  determination. 

In  this  way,  for  the  first  time,  we  can  obtain  on  a  boiler 
plant  the  "  critical  point  of  efficient  combustion,"  that  is,  the 
maximum  CO2  with  absence  of  CO  and  unburnt  gases. 

Ordinary  Combustion  Recorders,  that  is,  continuous  gas 
analysing  machines  for  determining  the  percentage  of  CO2 
only,  have  been  known  for  many  years.  Such  machines  will 
also  give  on  the  average  twenty  analyses  per  hour,  writing 
down  the  result,  together  with  the  time  of  analysis,  upon  a 
chart,  and  are  indispensable  for  modern  boiler  plant  testing 
and  control. 

For  some  extraordinary  reason  it  has  always  been  the 
custom  for  most  recognised  authorities  on  boiler  plant  testing 
to  disparage  the  CO2  Recorder. 


68  BOILER  PLANT  TESTING 

Thus  the  American  "  Mechanicals  "  Code  says  (p.  19)  : — 

'•  Instruments  known  as  CO2  Recorders  are  useful,  if  their 
accuracy  is  established." 

and  the  whole  of  the  rest  of  th&  space  (pp.  19,  46,  and  172- 
174)  devoted  to  flue  gas  analysis  is  taken  up  with  a  detailed 
description  of  the  "  Orsat"  and  "  Hempel  "  hand  apparatus. 
The  only  reference  in  the  "  Civils "  Code  is.  as  follows  (p. 
70):-  ' 

"If  the  percentage  of  carbon  dioxide  alone  is  required, 
the  '  Ados '  or  any  other  good  recording  instrument  may  be 
advantageously  used,  provided  that  it  is  checked  before  and 
during  the  trial." 

It  may  be  stated  that  the  "  Ados,"  a  German  machine, 
which  is  obviously  regarded  by  the  "  Civils  "  Code  as  the  best, 
is  so  completely  antiquated  that  the  last  instrument  was  sold 
in  this  country  fifteen  years  ago  (that  is  in  1907).  It  be- 
longed to  the  very  early  type  of  Combustion  Recorder  worked 
by  means  of  a  large  gasometer  actuated  by  the  chimney 
draught,  and  would  be  regarded  to-day  as  a  curiosity. 

The  "Civils"  Committee  seem  to  be  totally  unaware  that 
there  are  on  the  market  a  large  number  of  CO2  Recorders, 
almost  any  one  of  which  will  give  continuous  and  accurate 
records  of  the  percentage  of  CO2. 

When  the  "  Civils"  Code  was  revised  in  1913,  the  follow- 
ing instruments  were  on  sale  in  this  country  (as  they  are  to- 
day), either  by  the  British  manufacturers  or  their  agents,  or 
by  British  agents  of  foreign  manufacturers: — 

" Albion"  (British) 
"Auto"  (British) 
"  Bimeter  "  (British) 
"  Mono  "  (Swedish) 
"Sarco"  (British) 
"Simmance-Abady  "  (British) 
"Ward"  (British) 


FIG.  4. — "  Duplex  Mono,"  closed  as  when  working  normally  in  the  firehole. 

[To  face  p.  68. 


.it 


FIG>  5. — "  Duplex  Mono,"  front  view,  with  door  open. 


FIG.  6. — "  Duplex  Mono"  with  clock  and  other  mechanism  exposed  whilst 
the  machine  is  actually  running. 


FIG,  7.— Original  "  Mono''  automatic  gas  analysing  machine  for  CO  and 
unburnt  gases  only. 


CRITICISMS  OF  EXISTING  CODES  69 

and  there  are  now  the  following  additional  instruments  put  on 
the  British  market  since  1913  : — 

"  Cambridge  Electrical  "  (British) 

"  Hays"  (American) 

"W.R.  "  Combustion  Indicator  (British). 

There  must  be  almost  an  equal  number  of  different  makes 
of  CO2  Recorders  on  the  American  market,  and  there  are  also 
a  number  of  continental  machines,  chiefly  French,  German 
and  Dutch.  To  insinuate  that  all  these  instruments,  most  of 
which  have  been  on  the  market  for  years,  and  in  many  cases 
tested  and  certified  correct  by  the  National  Physical  Laboratory, 
cannot  be  used  for  determining  accurately  the  percentage  of 
CO2  on  a  boiler  test  is,  in  my  opinion,  not  only  ridiculous, 
but  grossly  unfair  to  most  makers  of  CO2  Recorders. 

It  might  be  thought  therefore  that,  as  far  as  the  "Civils  " 
Code  is  concerned,  the  section  relating  to  Flue  Gas  Analyses 
was  originally  drawn  up  in  the  years  1897-1902,  when 
there  may  have  been  a  good  excuse  for  ignoring  the  CO2 
Recorder,  and  that  the  Revision  Committee  of  1913  had 
practically  left  the  original  instructions  alone,  although  they 
were  by  this  time  hopelessly  out-of-date.  In  spite  of  this, 
however,  it  is  explicitly  stated  in  the  introductory  letter  (p.  4) 
that  one  of  the  sections  revised  was  the  sampling  and  analysis 
of  the  flue  gases. 

The  "  Civils "  Code,  as  seems  to  be  usual  when  any 
modern  appliance  is  considered,  throws  doubt  on  the  accuracy 
of  all  CO2  Recorders,  and  states  they  must  be  checked,  not 
only  before  the  trial,  but  during  it  as  well  (!).  It  may  be  re- 
marked that  to  test  the  accuracy  of  most  CO2  Recorders,  all 
that  is  necessary  is  to  let  the  instrument  run  on  air  for  a  few 
minutes  to  ensure  that  the  chart  record  is  exactly  0*0  percent. 
CO2.  To  talk  of  testing  a  CO2  Recorder  "during  "  the  trial, 
that  is  every  few  hours,  is  childish,  and  one  is  compelled  to 
come  to  the  conclusion  that  most  of  the  members  of  the 


70  BOILER  PLANT  TESTING 

"  Civils "   Committee  have  had   little  or  no  experience  with 
CO2  Recorders. 

I  would  like  to  guarantee  that  the  results  given  by  the 
average  CO2  Recorder  are  far  less  liable  to  error  than  the 
clumsy  methods  of  hand  anafysis  recommended  by  the 
"  Civils "  Code,  apart  from  the  fact  that  the  average  CO2 
Recorder  will  give  twenty  analyses  in  the  same  time  that  it 
takes  to  carry  out  three  or  four  analyses  by  hand. 

In  the  International  Code  I  would  make  it  compulsory 
to  use  a  CO2  Recorder  working  at  a  proper  speed  of  say 
fifteen  analyses  per  hour,  but  preferably  twenty  analyses,  so 
that  on  the  day's  trial  at  least  150  CO2  determinations  will 
be  carried  out.  Further,  I  would  suggest  that  the  CO2  Re 
corder  be  worked  day  and  night  on  the  plant  for  the  whole 
week's  check  test,  say  six  or  seven  hours  in  turn,  taking  flue 
gas  from  essential  portions,  such  as  the  downtake  or  side  flue 
of  "  Lancashire  "  boilers,  or  entrance  to  the  main  flue  of  each 
water-tube  boiler,  the  main  flue,  chimney  base,  etc.,  so  that 
during  the  whole  test  about  2 500  analyses  of  CO2  would  have 
been  carried  out.  There  is  very  little  trouble  in  obtaining  re- 
sults like  this  with  a  CO2  Recorder,  and  in  fact  it  is  much  less 
trouble  to  get  500  analyses  with  a  recorder  than  to  carry  out 
ten  analyses  by  hand. 

I  have  used  CO2  Recorders  on  every  one  of  the  tests  of 
400  boiler  plants  during  the  last  twelve  years  or  so,  and  it  is 
possible  to  take  a  CO2  Recorder  equipment  on  to  a  boiler 
plant  and  have  it  recording  the  percentage  of  CO2  on  a  chart 
at  the  rate  of  twenty  analyses  per  hour  in  fifteen  minutes  from 
the  time  of  arrival  on  the  plant.  For  convenience,  it  is  best 
to  have  the  instruments  taken  out  of  their  original  iron  cases 
and  installed  in  special  wooden  cases,  so  that  they  can  easily 
be  carried  about  and  hung  up  on  the  wall  close  to  the  boilers. 
Most  CO2  Recorders  use  a  trickle  of  water  (3  to  5  gallons  per 
hour)  to  drive  them,  and  the  easiest  method  is  to  place  on  the  top 
of  the  recorder  a  small  galvanised  iron  cistern,  specially  made 


CRITICISMS  OF  EXISTING  CODES  71 

to  fit,  and  holding  about  2  gallons  of  water.  All  that  is 
needed  to  work  the  instrument  is  a  bucket  of  water,  the  tank 
being  filled,  the  water  allowed  to  work  the  CO2  Recorder 
through  a  tap,  and  run  down  into  the  bucket  underneath, 
when  it  can  be  returned  to  the  tank  about  every  half-hour. 
At  the  points  of  analysis  ^-in.  W.I.  pipes  are  inserted  in  the 
flues,  and  provided  with  rubber  corks  through  which  a  piece 
of  glass  tube  is  inserted.  The  CO2  Recorder  is  then  hung  up 
near  the  chief  points,  and  connected  to  the  glass  tube  by 
means  of  a  thick  india-rubber  tube.  The  other  end  of  the 
CO2  Recorder  is  connected  in  the  same  way  to  another  piece 
of  i-in.  W.F.  pipe  inserted  in  the  chimney  base  or  adjacent 
main  flue.  A  convenient  way  to  do  this  is  to  take  several 
lengths  of  |-in.  W.I.  pipe  and  lay  them  on  the  floor  tempor- 
arily for  the  test.  By  this  arrangement  a  continuous  circula- 
tion of  flue  gas  is  ensured,  that  is  to  say,  if,  for  example,  the 
point  of  analysis  is  the  side  flues  of  a  "  Lancashire  "  boiler, 
the  draught  in  the  chimney  base  pulls  a  continual  current  of 
flue  gas  from  the  side  flues  through  the  CO2  Recorder,  and 
there  is  no  inaccuracy  due  to  "  lag  "  in  the  pipes. 

As  already  stated,  this  question  of  CO2  is  also  of  the  greatest 
importance  in  the  regular  working  of  a  boiler  plant,  and  it  is 
most  unfortunate,  to  say  the  least  of  it,  that  the  present 
standard  Boiler  Testing  Codes  should  not  only  be  out-of-date 
in  this  respect,  but  should  also  disparage  the  CO2  Recorder  in 
the  most  unjustifiable  manner. 

In  the  400  tests  since  1908,  with  which  I  have  been  as- 
sociated, there  is  included  approximately  400,000  analyses  of 
CO2  by  means  of  CO2  Recorders,  and  the  average  figures  of 
CO2  for  all  these  tests  is  only  7-5  per  cent,  and  I  should 
estimate  that  at  least  90  per  cent,  of  the  boiler  plants  of 
Great  Britain  are  unprovided  with  CO2  Recorders  in  running 
order. 

The  figures  for  the  400  plants  are  divided  as  follows  : — 


BOILER  PLANT  TESTING 


Percentage  of  CO2. 

No.  of 
Plants. 

Corresponding  Figure 
Expressed  as  a  Per- 
centage. 

12  per  cent,  and  over 

.             .             .          10 

2'5 

ii             ,,        ,        ,,           . 

10 

2'5 

10             „        ,        „ 

•         .       ..^39 

9-9 

9             „ 

.         .         .       48 

I2'I 

8            „                          .-•      . 

60 

re*2 

.^ 

3 

7            »«•       »       M          • 

91 

2^*4. 

6                      ,        „ 

:       .       .     58 

14-7 

5                          M               >               »                     • 

12*9 

Less  than  5  per  cent. 

.     27 

6-8 

Total 


394 


The  amount  of  calculated  loss  on  a  boiler  plant  due  to 
excess  air  is  shown  by  the  curve,   Fig.    8,  and  the  average 


OF      fVCt-     L.OS  S 


FIG.  8. — Curve  showing  the  fuel  loss  for  corresponding  percentage  of  CO2. 

figure  of  7*5   per  cent    CO2  corresponds  to  an  approximate 
calculated  loss  of  1 1 -o  per  cent,  in  the  coal  bill,  taking  14  per 

1  Six  plants  not  determined. 


CRITICISMS  OF  EXISTING  CODES  73 

cent,  as  the  maximum  CO2  obtainable.  That  is  to  say,  on 
the  annual  coal  bill  in  Gre  it  Britain  for  steam  generation  of 
90,000,000  tons,  the  loss  due  to  low  CO2  is  no  less  than 
9,900,000  tons  per  annum. 

With  regard  to  the  analysis  for  CO,  there  has  been  no 
option  but  to  use  hand  methods,  since  the  new  "  Duplex 
Mono,"  already  described,  is  only  just  coming  on  the 
market. 

The  recommendations  of  the  "  Civils  "  Code  with  regard 
to  the  hand  methods  to  be  used  for  the  analysis  of  flue  gases 
are  as  follows  (pp.  68-69)  : — 

"It  is  essential  that  the  temperature  of  the  flue  gases 
should  be  taken  at  the  same  point  as  that  from  which  the 
sample  for  analysis  is  drawn.  Great  care  must  be  taken  to 
avoid  their  dilution  by  air  leaking  between  the  boiler  and  the 
surrounding  brickwork,  through  cracks  in  the  brickwork  or 
through  ill-fitting  damper  frames  or  other  openings  in  the  ex- 
ternal flues. 

"  Since  the  gases  cannot  be  assumed  to  be  homogeneous, 
an  attempt  must  be  made  to  obtain  an  average  sample  through- 
out the  width  of  the  flue  ;  it  should  be  remembered,  moreover, 
that  (i)  the  gas  must  be  drawn  into  the  sample  tube  at  a  uni- 
form rate  per  hour,  (2)  the  gas  in  the  dead  space  between  the 
flue  and  the  sample  tube  must  be  eliminated,  (3)  the  gas  in 
the  sample  tube  must  not  be  allowed  to  diffuse  back  again 
into  the  main  tube  or  be  drawn  back  into  the  main  current 
by  sudden  changes  of  pressure."  l 

The  note  l  is  as  follows,  together  with  the  illustration  : — 

"  Condition  (3)  is  not  satisfied  by  any  of  the  ordinary  forms 
on  the  market.  That  shown  in  Fig.  6  (see  next  page)  has 
been  designed  by  Mr.  G.  Nevill  Huntly  to  fulfil  (i),  (2),  and 
(3).  The  gas  is  drawn  in  at  A,  the  dead  space  is  cleared  by 
sucking  at  B  ;  the  rate  at  which  the  gas  is  drawn  is  fixed 
by  the  distance  C-D,  and  this  can  be  increased  by  joining 
a  piece  of  glass  tube  with  rubber  to  D.  The  gas  in  E 
cannot  be  sucked  back  and  cannot  diffuse  back.  The  two 
3-way  taps  greatly  simplify  the  transference  of  gas  for 
analysis." 


74 


BOILER  PLANT  TESTING 


Mercury 


The  Code  then  goes  on  to  say  : — 

"It  is  often  necessary  and  advisable  to  carry  out  the 
analysis  of  the  gases  at  once.  One  of  the  most  convenient 
arrangements  for  this  purpose  is  the  '  Orsat '  apparatus,  as  it 
requires  no  supply  of  pure  water*  and  no  bottles  of  chemicals. 

:"  A  calibrated  'Orsat'  appar- 
atus with  mercury  as  a  confining 
liquid  gives  satisfactory  results 
for  carbon  dioxide,  but  is  not 
suitable  for  determining  carbonic 
oxide.  The  commercial  pattern 
is  not  recommended  for  the  de- 
termination of  oxygen.  Instruc- 
tions for  use  are  issued  by  the 
makers  of  the  different  instru- 
ments. 

"  If  the  gases  are  analysed  on 
the  spot  the  determination  of 
carbon  dioxide  alone  is  advisable  ; 
this  will  permit  of  tests  every 
fifteen  minutes.  If  a  fuller 
analysis  is  deemed  necessary  a 
series  of  continuous  samples 
should  be  drawn  off  into  small 
tubes  over  mercury  and  analysed 
either  during  or  as  soon  as  pos- 
sible after  the  trial." 

The  reason  of  all  these  com- 
plications is  not  very  clear,  but 
seems  to  be  due  to  the  fallacy 
in  the  "  Civils "  Code  of  trying 
to  calculate  the  efficiency  of  a 
boiler  plant  from  the  analysis  of 
the  flue  gases. 

It  is  most  extraordinary  that 
anyone  should  suggest  that  it  is  necessary  to  collect  samples 
of  flue  gas  over  mercury.  The  samples  taken  according  to 
the  methods  suggested  would  be  so  small  in  size  that  they 
could  not  possibly  be  an  average  of  the  vast  volume  of  flue 


0 

FIG.  9. 
(Fig.  6  in  the  "Civils"  Code.) 


CRITICISMS  OF  EXISTING  CODES  75 

gases  in  an  ordinary  boiler  plant,  and  if  we  are  going  to  use 
mercury  to  take  samples  even  approximating  to  a  true  average, 
we  should  require  hundredweights  of  mercury,  not  ounces. 

All  this  worry  about  "dead  space,"  "  diffusing  back," 
"changes  of  pressure,"  "temperature  of  the  gas,"  etc.,  is 
simply  a  waste  of  time  on  a  practical  boiler  test.  It  is  quite 
simple  to  obviate  it  by  drawing  two  or  three  samples  of  flue 
gas  into  an  "  Orsat "  or  other  hand  apparatus  one  after  the 
other,  and  only  analysing  the  last  sample.  In  any  case  there 
is  no  need  to  use  mercury,  and  a  solution  of  glycerine  and 
water  will  give  results  just  as  accurate  after  it  has  been  in 
contact  with  flue  gas  for  a  short  time  and  become  saturated. 
The  makers  of  the  "  Orsat "  apparatus  will  be  considerably 
astonished  to  learn  that  "  the  use  of  mercury  as  a  confining 
liquid"  is  recommended,  and  also  that  the  "commercial 
pattern  " — whatever  this  may  mean — is  not  suitable  for  the 
determination  of  oxygen.  In  any  case,  to  carry  out  only 
four  analyses  per  hour  is  nothing  like  sufficient  to  get  a 
proper  average,  and,  as  already  stated,  a  CO2  Recorder  will 
give  about  twenty  analyses  per  hour.  It  is  very  little  use  to 
take  "  snap"  tests  at  quarter  of  an  hour  intervals,  because  the 
composition  of  the  flue  gas  varies  almost  continuously,  as  a 
CO2  Recorder  soon  shows. 

In  order  to  collect  average  samples  of  flue  gas  over  a 
period,  the  "Civils  "  Code  states,  on  page  69  : — 

"  For  a  permanent  apparatus  the  arrangement  of  collect- 
ing-tubes illustrated  by  Mr.  Breckenridge  '2  is  probably  the 
best.  It  averages  gas  both  for  temperature  measurements 
and  gas  samples.  It  must,  however,  be  built  into  the  flue, 
and  hence  is  only  suitable  for  a  permanent  installation.  Mr. 
Breckenridge  has  shown,  however,  that  a  single  steel  tube 
closed  at  the  inner  end  and  perforated  with  a  series  of  holes  3 
throughout  its  length  takes  a  good  average  sample :  it  is 
readily  withdrawn  for  cleaning,  and  is  the  most  practical  form 
for  temporary  trials.  A  very  much  larger  quantity  of  gas 
must  be  drawn  from  the  flue  than  is  taken  for  analysis.  The 
sample  is  drawn  from  a  small  tube  joined  to  the  main  aspirating 


76  BOILER  PLANT  TESTING 

tube  ;  the  latter  may  be  of  half-inch  bore,  and  the  current 
may  be  conveniently  produced  by  a  steam-  or  water-ejector. 
A  test  should  be  made  for  gas-tightness  before  and  after  trial." 

The  notes  at  the  bottom  of  page  69  are  as  follows  : — 

"2  A  study  of  four  hundred1" steam  tests  made  at  the  Fuel 
Testing  Station,  St.  Louis,  Mo.,  1904-1906.  'United  States 
Geological  Survey,  Bulletin  325,  Washington,  1907, 'page  157." 

"3The  area  of  these  holes  must  be  small  as  compared 
with  that  of  the  bore  of  the  pipe,  otherwise  less  gas  will  enter 
the  tube  near  its  closed  end  than  elsewhere." 

According  therefore  to  the  "Civils"  Code  we  are  recom- 
mended, for  the  collection  of  large  samples  of  flue  gas,  to  use 
some  method  devised  years  ago  by  Professor  Breckenridge 
of  U.S.A.,  no  further  information  being  given.  Presumably 
when  a  boiler  test  is  contemplated  every  one  has  to  write  out 
to  the  United  States  Geological  Survey.  Accordingly  I  wrote 
to  Washington;  U.S.A.,  and  I  am  informed  (May,  1921)  very 
courteously  that  the  publication  in  question  has  been  out  of 
print  for  a  very  long  time  and  is  no  longer  available  from  any 
official  source  in  America.  It  will  give  some  idea  as  to  the 
practical  value  of  the  "  Civils  "  Code  when  it  recommends  an 
American  method  described  in  some  publication  twenty  years 
old,  and  which  has  apparently  been  out  of  print  for  years  in 
the  land  of  its  origin. 

I  fail  to  understand  what  is  the  need  of  all  this  trouble 
about  collecting  large  samples  of  flue  gas,  which  is  a  perfectly 
simple  operation.  For  a  few  pounds  one  can  buy  a  very 
efficient  gas  collecting  apparatus,  which  will  collect  say 
15,000  to  20,000  c.c.  of  flue  gas  at  any  desired  speed.  For 
example,  we  have  the  "  Hays"  Gas  Collector,  as  illustrated, 
Figs.  10  and  II. 

In  this  apparatus  a  water  supply  pipe  is  connected  to  the 
valve  WV  and  the  large  tank  of  the  collector  about  half  filled 
with  water,  with  a  pint  of  engine  oil  poured  on  the  top,  so 
that  the  water  in  the  collector  does  not  absorb  any  CO2. 
The  inlet  for  the  flue  gas  is  through  the  valve  GV  on  a  J-in. 


FIG.  10. — "  Hays  "  Automatic  Gas  Collector. 

[To  face  p.  77. 


CRITICISMS  OF  EXISTING  CODES 


77 


pipe.  To  work  the  collector  the  flue  gas  valve  GV  is  closed t 
the  valve  GC  opened  and  the  supply  of  water  turned  on  by 
opening  the  water  valve  WV  so  as  to  slowly  fill  the  whole  of  the 


FIG.  n. — Working  principle  of  the  "  Hays"  Automatic  Gas  Collector. 

collector  with  water  until  it  begins  to  flow  out  of  the  overflow 
OP,  when  the  valve  WV  is  shut  off.  The  valve  GC  is  then 
closed  and  the  flue  gas  valve  GV  opened. 


78  BOILER  PLANT  TESTING 

Water  will  then  flow  from  the  tank  T  into  the  flow  regu- 
lator R  and  be  discharged  through  the  drip  DC.  The  rate 
of  the  water,  that  is,  of  the  collection  of  the  flue  gas  through 
GV,  will  be  absolutely  steady,  depending  on  how  much  DC 
is  open  and  is  quite  regardless  of;4he  level  of  the  water  in  T. 
If  this  flow  regulator  is  not  provided,  a  simple  bottle  or 
cylinder  filled  with  water  and  allowed  to  empty  itself  will  not 
give  a  true  average  sample  over  a  number  of  hours  because, 
as  the  vessel  empties,  the  rate  of  flow  of  the  water  diminishes 
as  the  "head  "  of  the  water  is  less  in  the  apparatus. 

These  gas  collectors  can  be  installed  permanently  at 
different  points  of  the  plant,  and  one  instrument  retained  for 
carrying  about  for  temporary  installation  at  any  other  points 
of  the  plant.  The  sample  of  gas  for  analysis  is  withdrawn 
by  the  "Orsat"  apparatus  through  the  valve  GC  and  after 
analysis  the  gas  content  is  expelled  and  the  apparatus  is 
ready  for  use  again.  The  content  is  very  large,  about  17,500 
c.c.,  and  the  rate  of  collection  can  be  fairly  rapid,  say,  2000 
c.c.  per  hour. 

This  large  sample  of  gas  can  then  be  analysed  at  leisure 
for  CO2,  CO  and  oxygen,  and  the  figure  for  CO2  will  be  a 
useful  check  on  the  CO2  Recorder. 

I  would  suggest,  therefore,  that  the  International  Code 
insists  upon  a  large  sample  of  gas  being  taken  continuously, 
say  2000  c.c.  per  hour,  and  this  large  sample' be  then  analysed 
for  CO2,  CO  and  oxygen. 

The  next  question  is  the  points  at  which  to  draw  the 
samples  of  flue  gas,  and  this  concerns  also  the  methods  of 
calculation.  In  the  "  Civils  "  Code  flue  gas  analysis  is  intended 
primarily,  as  already  stated,  as  a  basis  for  the  •"  heat  balance  " 
of  the  plant  and  therefore  it  is  necessary  to  draw  samples  of 
gas  from  the  chimney  base,  that  is  the  final  exit  of  the  plant, 
so  as  to  calculate — from  the  analysis  of  the  gas — the  amount 
of  heat  lost  by  the  plant.  I  propose  to  discuss  in  detail  the 
method  of  calculation  in  later  pages,  but  will  say  here  that  in 
my  opinion  this  method  of  calculation  is  not  so  accurate,  and 


CRITICISMS  OF  EXISTING  CODES  79 

is    infinitely    more    complicated    and    troublesome,    than    the 
simple  method  based  on  the  actual  heat  in  the  coal. 

The  difficulties  of  the  "  Civils "  Code  method  are  shown 
by  the  following  paragraph  from  the  code  (p.  70) : — 

"  Since  the  amount  of  heat  carried  away  by  the  flue  gases 
is  proportional  to  their  volume,  and  this  volume  is  at  any 
instant  inversely  proportional  to  the  amount  of  carbon  dioxide 
by  volume,  the  mean  percentage  found  from  a  recording  in- 
strument or  from  the  analysis  of  an  average  gas  sample  is  not 
exactly  that  required.  The  error  from  this  cause,  with  a 
boiler  fired  from  a  mechanical  stoker,  will  probably  be  under 
cri  per  cent,  of  CO2 ;  with  a  hand-fired  boiler  it  may  be  as 
high  as  0-5  per  cent.;  with,  say,  10  per  cent,  of  carbon 
dioxide  in  the  flue  gas  this  would  mean  errors  of  I  per  cent, 
and  5  Per  cent,  respectively  in  the  heat  balance,  and  renders 
unnecessary  a  higher  accuracy  than  cri  per  cent,  on  the 
carbon  dioxide ;  for  this  accuracy  to  be  reached  the  gas 
sample  must  be  collected  over  mercury.  Considerable  errors 
may  occur  if  water  is  used,  and  the  next  best  fluid  to  mercury 
is  a  mixture  of  equal  volumes  of  glycerol  and  water,  when  the 
error  would  probably  not  exceed  O'4  per  cent. 

"  The  apparatus  used  for  gas  analysis,  therefore,  must  be 
correct  to  cri  per  cent,  for  carbon  dioxide  and  oxygen,  0*05 
per  cent,  for  carbon  monoxide,  and  cro2  for  methane.  These 
correspond  roughly  on  an  average  heat  balance  with  about 
0*25  per  cent,  of  the  total  heat  available. 

"When  boilers  are  fired  by  mechanical  stokers,  the  gas 
samples  may  be  drawn  directly  into  an  analysing  apparatus, 
but  when  the  firing  is  by  hand  continuous  collection  is  neces- 
sary to  ensure  correct  results. 

"When  all  the  gas  aspirated  passes  into  the  collecting- 
vessel  the  volume  of  the  aspirating-tube  must  be  very  small 
compared  with  the  volume  of  the  vessel  into  which  the  gas  is 
drawn,  otherwise  the  sample  collected  will  contain  little  besides 
the  gas  lying  in  the  tube  when  the  collection  was  begun." 

I  suggest  in  the  International  Code  to  abandon  entirely 
this  "  heat  balance  sheet "  method  of  calculation,  and  to  take 
the  samples  of  flue  gas  as  near  the  furnace  as  possible,  so  as 
to  get  proper  information  as  to  the  state  of  the  firing.  That 


8o  BOILER  PLANT  TESTING 

is  to  say,  the  sample  pipes,  say  ^-inch  W.I.,  should  be 
placed  in  the  downtake  or  side  flues  of  "  Lancashire "  or 
"Cornish"  boilers,  in  the  furnace  exit  of  water-tube  boilers, 
the  front  uptake  on  marine  boilers  and  so  on.  Samples  can 
of  course  be  taken  at  various  othfer  points  as  already  described, 
to  detect  air  leakages,  and  an  efficient  permanent  installation 
for  a  CO.,  Recorder,  with  connection  to  take  samples  for  hand 
analyses,  has  pipes  with  valves  connected  to  all  the  points,  so 
that  any  point  on  the  plant  can  be  switched  on  to  the  CO2 
Recorder  at  will,  whilst  at  the  same  time  the  gas  is  filtered 
from  dust  and  dirt  through  a  filter,  and  a  continuous  current 
of  gas  maintained  through  the  circuit  to  do  away  with  "  lag" 
errors. 

6.  The  Method  of  Measuring  the  Boiler  Feed- Water. 
—  In  order  to  measure  the  amount  of  water  evaporated  there  are 
two  general  methods  that  can  be  adopted,  namely,  (i)  weigh- 
ing the  water  or  measuring  its  volume  in  tanks,  and  (2)  using 
a  water  meter.  A  third  possibility,  that  of  measuring  the 
output  of  the  plant  as  actual  steam  by  means  of  steam  meters, 
will  be  discussed  later  (p.  131). 

The  "  Civils  "  Code  gives  a  most  elaborate  account,  occupy- 
ing no  less  than  eleven  pages  (pp.  38-49),  of  the  methods  to 
be  used,  insisting  on  the  tank  method  only,  even  at  sea. 
The  reference  to  water  meters  is  as  follows  (p.  46,  No.  6, 
"Feed  Meters"):— 

"  Feed  meters  are  not  recommended  for  scientific  trials, 
but  as  some  makes  appear  to  be  capable  of  giving  results 
within  I  per  cent,  of  accuracy,  they  may  be  usefully  employed 
in  many  cases  when  it  is  desired  to  obtain  an  approximate 
idea  of  the  normal  performance  of  the  boilers ;  they  should, 
however,  be  calibrated  before  and  after  the  trial  with  water  at 
the  temperature  of  the  feed.  A  "  Venturi "  meter,  for  instance, 
or  a  notch  gauge,  may  be  used  for  the  continuous  measure- 
ment of  water  when  the  quantity  is  large,  and  the  flow  is 
fairly  steady,  as  giving  fairly  accurate  results." 

This  is  altogether  a  most  remarkable  paragraph.  It  is 
stated  that  some  meters  "appear  to  be  capable"  of  giving 


CRITICISMS  OF  EXISTING  CODES  81 

results  accurate  to  I  per  cent,  in  which  case  they  can  be  used 
when  "  approximate "  results  are  obtained.  If  any  water 
meter  is  accurate  to  I  per  cent.,  then  in  my  opinion  it  is 
probably  more  accurate  than  the  "  Civils  "  method  of  weighed 
tanks,  and  much  more  suitable  for  all  boiler  trials,  no  matter 
how  "scientific".  I  have  had  a  fairly  long  experience  of 
boiler  trials  carried  out  by  means  of  tanks,  and  even  when  the 
greatest  care  is  taken,  very  few  trials  are  accurate  to  I  per 
cent,  by  this  method.  The  operation  is  in  practice  extremely 
clumsy  and  tedious,  and  the  observers  quickly  get  tired  of  the 
monotonous  operations,  so  that  errors  soon  tend  to  creep  in 
every  time  a  tank  is  filled  and  emptied.  Further,  whilst  a 
meter  can  be  calibrated  "before  and  after  the  trial "  and  any 
errors  detected,  it  is  impossible  to  do  this  with  the  tank 
method,  although  the  error  is  likely  to  be  as  much,  if  not 
more,  than  a  water  meter. 

As  with  CO2  Recorders,  the  above  paragraph  may  have 
applied  to  1897-1901,  when  the  "Civils"  Code  originated, 
but  to  say  that  it  applies  at  the  present  time,  or  even  in  1913 
when  the  Code  was  revised,  is  quite  wrong.  There  are  at  the 
present  time  nearly  twenty  different  makes  of  boiler  feed 
meter,  British  and  American,  on  sale  in  this  country ;  apart 
from  many  continental  meters,  and  for  the  "  Civils  "  Code  to 
maintain  that  all  these  meters  are  not  accurate  enough  for  the 
very  purpose  for  which  they  are  specifically  designed,  namely, 
boiler  testing,  is  a  very  strong  statement,  to  say  the  least  of 
it,  and  one  which  is  made  without  any  apparent  justification. 

The  American  "  Mechanicals "  Code  is,  as  usual,  much 
more  up-to-date  and  states  the  following  (p.  12): — 

"  9$.  Water  Weighing  and  Measuring  Apparatus. — 
(i)  Feed-water. — Wherever  practicable  the  feed-water  should 
be  weighed,  especially  for  guarantee  tests.  The  most  satis- 
factory and  reliable  apparatus  for  this  purpose  consists 
of  one  or  more  tanks  each  placed  on  platform  scales,  these 
being  elevated  a  sufficient  distance  above  the  floor  to 
empty  into  a  receiving  tank  placed  below,  the  latter  being 

6 


82  BOILER  PLANT  TESTING 

connected  to  the  feed  pump.  Where  only  one  weighing  tank 
is  used  the  receiving  tank  should  be  of  larger  size  than  the 
weighing  tank,  to  afford  sufficient  reserve  supply  to  the  pump 
while  the  upper  tank  is  filling.  If  a  single  weighing  tank  is 
used  it  should  preferably  be  of  such  capacity  as  to  require 
emptying  not  oftener  than  every  five  minutes.  If  two  or 
more  tanks  are  used,  the  intervals  between  successive  empty- 
ings should  not  be  less  than  three  minutes.  Measuring  tanks 
calibrated  by  weighing  may  also  be  used. 

"  In  tests  of  complete  steam  power  plants,  where  it  is 
required  to  measure  the  feed-water  without  unnecessary  change 
in  the  working  conditions,  a  water  meter  may  be  employed. 
Meter  measurement  may  also  be  required  in  many  other  cases, 
such  as  locomotive  and  marine  service.  The  accuracy  of 
meters  should  be  determined  by  calibration  in  place  under  the 
conditions  of  use. 

"  If  a  large  quantity  of  water  is  to  be  measured,  an  automatic 
water-weigher,  a  rotary,  disk,  or  Venturi  meter,  a  weir,  or 
some  form  of  orifice  measurement  may  be  employed.  In  any 
case  the  measuring  apparatus  should  be  calibrated  under  the 
conditions  of  use,  unless  its  design  is  such  that  standard 
formulae  and  constants  may  be  applied  for  determining  the 
discharge.  If  recording  mechanism  is  employed  in  connection 
with  orifice  or  weir  measuring  apparatus,  make  sure  that  its 
record  is  reliable." 

This  statement  is,  however,  not  quite  fair  to  water  meters 
in  general,  and  most  meters  can  be  used  quite  well  for  the 
smallest  boiler  plants. 

It  will  be  noted  that  the  wording  as  regards  "Venturi" 
and  "  Notch  "  meters  is  very  much  the  same  in  the  two  Codes, 
and  it  is  very  curious  that  the  "Civils"  Code  has  quite  a 
number  of  references  to  specific  American  conditions,  such  as 
the  "Barrus"  calorimeter  (p.  57),  the  "  Breckenridge  "  method 
of  gas  collection  (p.  75),  and  the  question  of  three  hours' 
duration  of  the  test  (p.  53). 

It  is  interesting  to  give  the  names  and  types  of  the  various 
boiler  feed  meters  on  the  British  market.  Such  meters  are 
divided  into  two  general  classes  :  (a)  open,  non-pressure  types, 
and  (<£)  closed,  pressure  types. 


CRITICISMS  OF  EXISTING  CODES  83 

The  first  class  consist  of  (i)  Automatic  Water  Weighing 
Machines  in  which  a  small  tank  is  continually  filled  with  water 
to  a  certain  weight,  when  it  is  released,  and  the  water 
falls  into  the  boiler  feed  tank,  the  number  of  such  small 
weighed  tanks  being  recorded  on  a  train  of  wheels  mechanism. 
Of  this  type  there  is  the  "Avery  Automatic  Water  Weigher," 
the  " Leinert  Meter "  and  the  "  Sarco  Tippling  Meter".  (2) 
"  V  Notch  Meters"  in  which  the  water  flows  through  a  "  V  " 
notch  of  given  dimensions,  and,  by  means  of  a  float  mechanism, 
a  continuous  record  is  kept  of  the  height  of  the  water  in  the 
notch,  the  amount  of  water  passing  being  proportional  to  the 
height  in  the  notch.  Of  meters  on  this  principle  there  is  the 
''Bailey  Meter,"  the  "Kent  V  Notch  Recorder,"  the  "  Lea 
V  Notch  Recorder,"  the  "  Paterson  Fluxograph"  and  the 
"Rheograph  Water  Flow  Recorder".  (3)  "Weir  Meters!' 
on  the  same  principle  as  the  last,  but  using  a  "  weir  "  instead 
of  a  ''V"  notch,  represented  by  the  "  Simmance-Abady 
Precision  Meter". 

In  the  second  class,  the  meter  is  placed  between  the 
boiler  feed  pump  and  the  economiser,  or,  in  fact,  at  any  point 
of  the  circuit  between  the  feed  pump  discharge  and  the  boiler 
feed  valve.  In  the  case  of  an  injector  the  meter  must  be  on 
the  suction  side,  and  can  also,  if  necessary,  be  on  the  pump 
suction.  Pressure  meters  are  divided  into  the  following 
classes  : — 

(1)  Piston  Meters   in    which    the    pressure    of  the    water 
actuates  in  its  travel    a  double  acting    piston,    so  that  each 
stroke  of  this  piston  represents  a  definite  amount  of  water,  the 
number    of    strokes    being    recorded    by  a    train    of  wheels 
mechanism.     Meters  of  this  type  are  the  "  Kennedy,"  "  Sarco  " 
and  " Worthington  Duplex". 

(2)  Rotary  Meters,   in  which   the   pressure   of   the   water 
actuates  a    rotary  displacer,  wheel,  disc,  or   other  appliance, 
one  revolution  corresponding  to  a  definite  amount  of  water, 
and  the  number  of  revolutions  being  recorded  by  means  of 
the  usual  train  of  wheels  mechanism.     This  type  is  represented 


84  BOILER  PLANT  TESTING 

by  the  "Kent  Uniform"  Meter,  the  "  Leeds "  Meter,  the 
"Sarco  Disc"  Meter,  the  "  Siemans  Disc"  Meter,  the 
"  Siemans'  and  Adamson "  Meter,  and  the  "  Worthington 
Turbine  "  Meter. 

(3)  "  Venturi  Meters"  on  the  principal  of  the  "  Venturi  " 
tube,  such  as  the  "Bailey  Fluid  Meter  €4,"  and  the  ''British 
Thomson-Houston  "  Meter. 

A  water  meter  has  two  very  great  advantages  over  any 
tank  method.  In  the  first  place,  it  is  much  more  convenient 
and  reduces  the  trouble  and  worry  of  boiler  testing  to  an 
astonishing  degree.  Secondly,  it  has  the  very  great  advantage 
that  it  enables  a  boiler  plant  to  be  run  on  the  only  possible 
lines  for  the  highest  of  efficiency,  namely,  that  of  continuous 
testing  all  the  year  round.  It  is  absolutely  essential  that  a 
weekly  record  be  kept  of  the  water  evaporated  on  a  boiler 
plant,  together  with  the  amount  and  analysis  of  coal  burnt, 
and  other  vital  figures,  and  the  water  meter  is  practically  the 
only  possible  method  of  doing  this.  The  "  Civils  "  Code  in 
this  respect  is  not  devised'  on  practical  lines,  and  is  obviously 
only  intended  for  an  occasional  test,  as  it  would  be  almost 
impossible  to  carry  out  even  a  week's  trial  on  the  methods 
recommended.  Eor  trials  at  sea,  and  for  locomotives,  the 
advantages  of  the  closed  type  of  meter  will  be  obvious. 

The  trouble  is,  of  course,  that  all  water  meters  are  not 
equally  accurate,  and  it  would  be  rather  a  delicate  matter  for 
me  to  attempt  to  give  an  opinion  as  to  the  accuracy  or  other- 
wise of  any  individual  meter.  I  would  suggest  that  this  be 
one  of  the  investigations  to  be  carried  out  by  the  Committees 
engaged  in  devising  the  International  Code,  and  that  a  list  of 
"  approved "  meters  be  issued  after  such  investigations  are 
complete  ;  any  one  of  these  approved  meters,  under  suitable 
conditions,  to  be  allowed  for  use  on  an  official  test,  in  addition, 
of  course,  to  the  tank  method  if  desired. 

Whatever  meter  is  used,  it  must  be  installed  with  a  bye- 
pass  arrangement,  and  a  testing  tank.  The  method  of  instal- 
lation I  recommend,  from  long  practical  experience,  for  per- 


CRITICISMS  OF  EXISTING  CODES 


manent  installation  for  a  pressure  type  of  meter  is  illustrated 
in  Fig.  12. 

A  is  the  water  meter  and  F  a  small  calibrated  test  tank, 
(say    6000  Ibs.   capacity).       Normally,  the    feed-water    flows 


srppy/nuE  .&R*LUL  Siipg  Type, 
fit 


Sy\HPLlH^    C/^STIN6. 


TESTING  TANK.. 


FiG.  12. — Typical  installation  Recommended  for  a  boiler  feed  meter 
(pressure  type). 

through  the  stop  valve  Bb  the  sampling  casting  E,  the 
meter  A,  the  combined  stop  and  check  valve  C  and  on  to 
the  boiler  plant.  Bj  is  an  ordinary  parallel  slide  stop  valve, 
E  is  a  simple  "sampling  casting"  of  my  own  design,  con- 
taining a  thermometer  socket  to  read  the  temperature  of  the 
feed-water  actually  passing  through  the  meter,  whilst  at  the 


86  BOILER  PLANT  TESTING 

same  time  a  tap  is  provided  to  take  a  sample  of  the  water. 
The  valve  C  is  an  ordinary  stop  valve,  but  loose  on  the 
spindle  so  that  it  acts  also  as  a  non-return  (check)  valve. 
The  object  of  this  is  to  obviate  any  back  pressure  action  on 
the  meter  and  make  the  travel,»in  the  meter  absolutely  "  for- 
ward "  only.  On  the  bye-pass  is  a  safety  valve  D  as  a  safe- 
guard to  the  meter,  and  in  this  position  it  acts  for  both  bye- 
pass  and  normal  feeding.  In  case  of  necessity  the  meter  can 
be  shut  out  of  the  circuit  by  closing  valves  Bx  and  C  and 
opening  valve  B2.  In  order  to  test  the  meter  when  running 
normally,  all  that  is  necessary  is  to  shut  valve  C  and  open 
valve  B3  to  the  test  tank. 

I  devised  and  used  the  above  method  long  before  I  ever 
read  the  American  "  Mechanicals"  Code,  but  in  this  Code  the 
following  almost  identical  method  is  recommended  (p.  155)  : — 

"  Calibrating  Water  Meters. — 227.  Referring  to  Fig.  2, 
two  tees  A  and  B  are  placed  in  the  feed  pipe  and  between 
them  two  valves  C  and  D.  The  meter  is  connected  between 
the  outlets  of  the  tees  A  and  B,  and  the  valves  E  and  F  are 
placed  one  on  each  side  of  the  meter.  When  the  meter  is 
running,  the  valves  E  and  F  are  opened,  and  the  valves  C 
and  D  closed.  A  small  bleeder  G  is  kept  open  to  make  sure 
that  there  is  no  leakage.  A  gage  is  attached  at  H.  When 
the  meter  is  tested,  the  valves  C,  D  and  F  are  closed,  and  the 
valves  E  and  I  are  opened.  The  water  flows  from  the  valve 
I  to  a  tank  on  platform  scales.  In  testing  the  meter,  the 
water  is  throttled  at  the  valve  I  to  obtain  the  desired  rate  of 
discharge,  the  gauge  meanwhile  showing  the  working  pressure. 
The  piping  leading  from  the  valve  I  to  the  tank  is  arranged 
with  a  swinging  joint,  consisting  merely  of  a  loosely  fitting 
elbow,  so  that  it  can  be  readily  turned  into  the  tank  or  away 
from  it.  When  the  desired  speed  has  been  secured,  the  end 
of  the  pipe  is  swung  into  the  tank  at  the  instant  the  pointer 
of  the  meter  is  opposite  some  graduation  mark  on  the  dial. 
When  the  required  number  of  cubic  feet  are  discharged,  the 
pipe  is  swung  away.  The  tests  should  start  and  stop  at  the 
same  graduation  mark  on  the  first  dial,  and  continued  until  at 
least  10  or  20  cub.  ft.  are  discharged  for  one  test.  The  tank  is 
weighed  before  and  after  filling. 


CRITICISMS  OF  EXISTING  CODES  87 

'•  228.  The  water  passing  the  meter  should  always  be 
under  pressure  so  that  any  air  in  the  meter  may  be  discharged 
through  the  vents  provided  for  this  purpose.  Care  should  be 
taken  that  there  is  no  unnecessary  air  drawn  into  the  feed- 
water.  The  meter  should  be  tested  before  and  after  the  trial, 
and  repeated  calibrations  should  be  made  to  obtain  confirmative 
results. 

"  229.  Fig.  2  1  and  the  description  apply  to  a  piston  meter, 
but  any  other  type  of  meter  carrying  water  under  pressure 
may  be  calibrated  in  the  same  manner." 


FIG.  !3. — Meter  calibration.     (American  Mechanical  Engineer's  Code,  Fig.  2.) 

The  note  x  says  : — 

<(1  Reproduced  from  'Trans.  Am.  Soc.  M.  E.,J  vol.  24,  p. 
724,  fig.  1 1 8." 

By  such  methods  the  accuracy  of  the  meter  can  be  checked 
at  any  time  in  less  than  half  an  hour.  The  "  Civils"  Code 
might  very  well  have  stated  that  one  of  the  advantages  of  the 
tank  method  is  that  it  is  always  certain  in  the  sense  that  any 
error  is  small,  whereas  if  a  meter  does  go  wrong,  the  error 
may  be  very  great  and  uncertain,  as  it  may  be  high  or  low,  or 
commence  suddenly.  By  using  a  testing  tank,  therefore,  as 


88  BOILER  PLANT  TESTING 

described,  in  conjunction  with  a  water  meter,  the  possibilities 
of  error  are  reduced  to  a  minimum,  and  comparable,  for 
example,  only  to  the  possibility  of  making  a  mistake  in  the 
actual  number  of  tanks  used  on  a  test  according  to  the 
"  Civils  "  Code.  For' a  very  large  boiler  plant  and  a  per- 
manent installation,  I  recommend,  as  an  absolute  certainty, 
two  different  makes  of  meter  in  series  with  testing  tank,  as 
the  expense  of  an  extra  meter  is  trifling  in  comparison  with 
the  advantages  obtained. 

7.  Moisture  in  the  Steam. — Another  of  the  great  practical 
difficulties  in  the  way  of  a  scientifically  accurate  boiler  plant 
test  is  that  steam,  unless  superheated,  always  contains  some 
water.  The  amount  is  generally  I  to  2  per  cent,  but  may  be 
anything  from  zero  to  even  5  per  cent.  Theoretically,  of 
course,  such  water  must  be  deducted,  as  it  is  included  as 
steam  (with  the  full  absorption  of  latent  heat)  in  the  amount 
of  water  evaporated,  and  if  not  deducted,  makes  the  efficiency 
of  the  boiler  plant  too  high. 

Both  the  "  Civils"  and  the  American  ''Mechanicals" 
Codes  state  that  this  moisture  in  the  steam  must  be  determined, 
and  deducted  in  calculating  the  efficiency.  The  "  Civils  " 
Code,  however,  goes  on  to  point  out  the  difficulties  as 
follows  (p.  52):— 

"  No.  1 5.  Measuring  the  Moisture  in  Steam. — Up  to  a 
certain  limit,  depending  on  the  steam  velocity,  the  moisture 
can  be  measured  by  one  of  the  forms  of  calorimeter  in  the 
market ;  these  instruments  are  not  generally  reliable  when  the 
moisture  exceeds  about  2  per  cent,  as  it  then  appears  to  creep 
along  the  walls  of  the  pipes  and  does  not  all  enter  the  calori- 
meter. It  is  therefore  desirable  to  provide  the  steam-pipe 
with  a  steam-drier,  and  to  measure  the  quantity  of  water 
which  is  discharged  by  an  automatic  trap ;  and  also  to 
measure  the  moisture  of  the  steam  after  it  has  passed  the 
steam-drier.  Opinions  differ  as  to  whether  it  is  best  to  collect 
the  steam  by  a  perforated  tube  fixed  across  the  diameter  of 
the  steam-pipe  or  by  a  tube  arranged  to  collect  from  the 
centre  only  of  the  steam-pipe,  but  the  former  method  is  in 
more  general  favour." 


CRITICISMS  OF  EXISTING  CODES  89 

Further  references  to  the  question  of  moisture  in  steam 
are  (p.  78):- 

"  Full  information  should  be  given  as  to  the  method  of 
determining  the  weight  of  the  moisture  present  in  the  steam, 
and  how  it  was  trapped,  or  collected,  and  weighed."  l 

The  note  l  says  : — 

"See  paper  by  Dr.  W.  C.  Unwin,  <  Proc.  Inst.  Mech.  E.,' 
1895,  P.  31." 

The  chief  difficulties  are  that  the  ordinary  steam  calori- 
meters, whether  of  the  throttling  or  separating  type,  are  not 
very  accurate  at  the  best  of  times,  and  particularly,  as  stated, 
when  the  moisture  is  over  2  per  cent. ;  there  is  no  known  satis- 
factory method  of  obtaining  a  true  average  sample  of  steam; 
and  further,  the  steam  also  has  generally  a  violent  swirling 
motion  as  it  passes  along  the  pipes,  especially  in  the 
neighbourhood  of  bends,  valves,  etc.,  which  does  not  make 
the  sampling  any  easier. 

The  "  Civils  "  Code  is  compelled,  therefore,  to  recommend 
the  laborious  proceeding  of  inserting  a  special  steam  drier  in 
the  steam  pipe,  measuring  the  amount  of  water  discharged 
from  the  drier  by  means  of  an  automatic  trap,  and  then  deter- 
mining the  moisture  left  in  the  steam,  by  means  of  a  steam 
calorimeter,  after  it  has  passed  the  steam  drier.  In  this  con- 
nection it  may  be  pointed  out  that  the  modern  type  of  steam- 
drier  such  as  the  "  Stefco  "  and  the  "  Tracy  "  are  not  placed 
in  the  steam  pipe  circuits,  but  in  the  boiler  itself.  There  is, 
consequently,  no  trouble  in  fitting  them,  and  they  will  separate 
the  moisture  so  that  the  steam  contains  certainly  less  than 
I  per  cent,  and  may  be  absolutely  dry. 

It  is  also  very  difficult  to  know  where  to  take  a  sample  of 
steam  issuing  from  a  boiler.  If  it  is  drawn  from  the  vertical 
branch  pipe  a  few  inches  above  the  boiler  shell  there  is  trouble 
due  to  "  showers  "  of  condensed  steam,  and  the  percentage  of 
moisture  shown  is  apt  to  be  too  high.  On  the  other  hand, 


90  BOILER  PLANT  TESTING 

the  sample  must  be  taken  close  to  the  boiler  to  avoid  inac- 
curacies due  to  cooling  and  condensation. 

The  American  "  Mechanicals  "  Code  states  (p.  18)  :— 

"9/#.  Steam  Calorimeters. — The  most  satisfactory  in- 
struments for  determining  the  ^amount  of  moisture  in  steam 
are  calorimeters  that  operate  upon  the  throttling  principle,  or 
that  combine  the  throttling  and  separating  principles ;  the 
orifice  used  being  of  such  size  as  to  throttle  to  atmospheric 
pressure,  and  the  instrument  being  provided  with  two  ther- 
mometers, one  showing  the  temperature  above  the  orifice  and 
the  other  that  below  it.  If  no  commercial  make  of  calorimeter 
is  available  on  a  test,  an  instrument  of  the  throttling  type  can 
be  made  of  pipe  fittings  as  shown  in  Appendix  No.  11.  In- 
struments working  on  the  separating  principle  alone  may  also 
be  employed  ;  also  certain  forms  of  electric  calorimeters.  See 
'Trans.  Am.  Soc.  M.  E./  vol.  28,  p.  616." 

The  Appendix  2  is  a  detailed  description  of  a  throttling 
calorimeter.  As  regards  the  method  of  sampling  the  steam 
the  American  "  Mechanicals "  Code  has  the  following  (p. 
35):- 

"  C.  Sampling  Steam. — 28.  Construct  a  sampling  pipe 
or  nozzle  made  of  ^-in.  iron  pipe  and  insert  it  in  the  steam 
main  at  a  point  where  the  entrained  moisture  is  likely  to  be 
most  thoroughly  mixed.  The  inner  end  of  the  pipe,  which 
should  extend  nearly  across  to  the  opposite  side  of  the  main, 
should  be  closed  and  the  interior  portion  perforated  with  not 
less  than  twenty  i-in.  holes  equally  distributed  from  end  to  end 
and  preferably  drilled  in  irregular  or  spiral  rows,  with  the 
first  hole  not  less  than  half  an  inch  from  the  wall  of  the  pipe. 

"The  sampling  pipe  should  not  be  placed  near  a  point 
where  water  may  pocket  or  where  such  water  may  affect  the 
amount  of  moisture  contained  in  the  sample.  Where  non- 
return valves  are  used,  or  where  there  are  horizontal  connec- 
tions leading  from  the  boiler  to  a  vertical  outlet,  water  may 
collect  at  the  lower  end  of  the  uptake  pipe  and  be  blown  up- 
ward in  a  spray  which  will  not  be  carried  away  by  the  steam 
owing  to  a  lack  of  velocity.  A  sample  taken  from  the  lower 
part  of  this  pipe  will  show  a  greater  amount  of  moisture  than 
a  true  sample.  With  goose-neck  connections  a  small  amount 


CRITICISMS  OF  EXISTING  CODES  91 

of  water  may  collect  on  the  bottom  of  the  pipe  near  the  upper 
end  where  the  inclination  is  such  that  the  tendency  to  flow 
backward  is  ordinarily  counterbalanced  by  the  flow  of  steam 
forward  over  its  surface  ;  but  when  the  velocity  momentarily 
decreases  the  water  flows  back  to  the  lower  end  of  the  goose- 
neck and  increases  the  moisture  at  that  point,  making  it  an  un- 
desirable location  for  sampling.  In  any  case  it  should  be  borne 
in  mind  that  with  low  velocities  the  tendency  is  for  drops  of 
entrained  water  to  settle  to  the  bottom  of  the  pipe,  and  to  be 
temporarily  broken  up  into  spray  whenever  an  abrupt  bend  or 
other  disturbance  is  met. 

"  29.  If  it  is  necessary  to  attach  the  sampling  nozzle  at  a 
point  near  the  end  of  a  long  horizontal  run,  a  drip  pipe  should 
be  provided  a  short  distance  in  front  of  the  nozzle,  preferably 
at  a  pocket  formed  by  some  fitting,  and  the  water  running 
along  the  bottom  of  the  main  drawn  off,  weighed,  and  added 
to  the  moisture  shown  by  the  calorimeter  ;  or  better,  a  steam 
separator  should  be  installed  at  the  point  noted. 

"  30.  In  testing  a  stationary  boiler  the  sampling  pipe  should 
be  located  as  near  as  practicable  to  the  boiler,  and  the  same  is 
true  as  regards  the  thermometer-well  when  the  steam  is  super- 
heated." 

The  use  of  a  steam  calorimeter  at  all  is  a  laborious,  hot  and 
generally  most  unpleasant  job,  and  I  am  afraid  that  if  the 
"  Civils  "  Code  is  to  be  following  in  this  respect,  there  will  be 
in  practice  more  trouble  in  determining  the  moisture  in  the 
steam  than  in  testing  all  the  rest  of  the  plant  put  together. 
As  a  consequence,  in  very  few  boiler  trials  is  the  moisture  in 
the  steam  determined,  and  practically  all  the  400  boiler  tests 
we  have  carried  out  have  been  average  in  this  respect. 

I  would  suggest  that  in  the  International  Code,  the  deter- 
mination of  the  moisture  in  the  steam  be  abandoned  entirely, 
as  the  results  are  dubious  and  not  worth  the  trouble,  and  that 
this  question  be  investigated  by  a  future  Committee  with  a 
view  to  settling  the  point  definitely.  It  certainly  seems  a 
feasible  proposition  to  insert  steam  driers  in  the  boilers  them- 
selves, as  already  mentioned,  since  these  modern  driers  in- 
crease the  economy  of  the  boiler  plant,  and  the  steam  could 
then  be  taken  as  free  from  moisture. 


92  BOILER  PLANT  TESTING 

In  plants  fitted  with  superheaters  there  will  of  course  be 
no  inaccuracy,  but,  unfortunately,  superheaters  are  compara- 
tively little  used  in  this  country.  Thus  out  of  the  400  plants 
only  114(285  per  cent.)  were  fitted  with  superheaters,  and 
most  of  these  only  partially  equipped.  For  plants  without 
superheaters  the  efficiency  results  would  therefore  be  a  little 
too  high. 

In  practice,  however,  by  a  little  care  this  error  can  be  re- 
duced to  a  minimum  by  keeping  the  water  at  a  reasonable 
height  in  the  gauge  glasses.  Most  boilers  in  Great  Britain  are 
working  much  below  their  proper  rated  output,  so  that 
moisture  in  the  steam  is  not  excessive,  and  for  testing  any 
plant  for  guarantee  the  amount  of  evaporation  can  be  specified 
so  that  the  conditions  with  and  without  the  appliance  will  be 
the  same  in  this  respect.  As  usual,  of  course,  the  moisture 
determinations,  by  means  of  a  steam  calorimeter,  can  always 
be  added  to  the  International  Code  by  arrangement  for  any 
particular  test. 

8.  Specific  Heat  of  Superheated  Steam.— With  regard  to 
this  point,  the  "  Civils  "  Code  gives  the  following  (p.  50)  : — 

"No.  13.  Specific  Heat  of  Superheated  Steam. — Experi- 
ments have  for  some  years  past  been  carried  out  with  the 
object  of  ascertaining  the  amount  of  heat  that  is  represented 
by  various  degrees  of  superheat,  but  definite  results  have  not 
yet  been  obtained. 

"  As  far  as  our  present  knowledge  extends  the  value  0-48 
may  be  adopted  for  the  purposes  of  this  report.  Every  100°  F. 
superheat  then  represents  about  4  per  cent,  of  the  total  heat 
of  the  steam,  and  an  error  of  croi  in  the  value  of  this  specific 
heat  wonld  not  affect  the  results  of  the  calculations  by  more 
than  o-i  per  cent.1 " 

The  note  *,  at  the  bottom  of  the  page,  is  as  follows  : — 

" l  The  values  given  in  Marks  and  Davis's  Tables  are 
generally  accepted.  A  chart  giving  '  mean  specific  heat '  of 
superheated  steam  over  a  wide  range  of  temperatures  and 
pressures  will  be  found  in  '  Principles  of  Thermodynamics,' 
by  G.  A.  Goodenough.  2nd  ed.  London,  1912." 


CRITICISMS  OF  EXISTING  CODES 


93 


This  hardly  seems  to  be  the  right  point  of  view  in  1922. 
0*48  is  the  specific  heat   figure  as  originally  determined  by 
Regnault  and  Him.      Mini's  formulae  was  : — 
Specific  heat  at  constant  pressure  is  =  0-4304  +  0*0003779  T 

(T  =  temp.  °F.) 


0-500 


0450 


40  50C 

TEMPERATURE 


700 


750 


Of    SUPEK  HEATED 


FIG.  14.  —  Curve  showing  the  specific  heat  of  superheated  steam 
(Knoblauch  and  Jakob's  figures). 

This,  however,  is  only  correct  for  atmospheric  pressure.  The 
figures  for  the  specific  heat  of  superheated  steam  at  different 
pressures  have  been  determined  with  great  accuracy  by  Knob- 
lauch and  Jakob,  of  the  Royal  Technical  University,  Munich, 
and  are  given  in  any  book  on  steam  tables,  in  the  form 
of  the  curve  Fig.  14,  and  I  would  suggest,  therefore,  that  in 
the  International  Code  these  figures  be  taken  as  official  for 


94  BOILER   PLANT  TESTING 

the  calculations.  The  figures  vary  from  about  0*45  to 
0*685  >  thus,  in  the  examples  I  have  given  in  the  specimen 
Complete  Report  according  to  the  suggested  International 
Code  (p.  149),  the  temperature  of  the  superheated  steam  is 
559°  F.  and  the  boiler' pressure  162  Ibs.  absolute,  with  a 
corresponding  saturation  temperature  of  364 '2°  F.  From 
Knoblauch  and  Jakob's  table,  the  specific  heat  of  super- 
heated steam  for  these  conditions  is  0-54,  wh'ereas  of  course 
the  "Civils"  Code  would  take  it  as  0-48.  The  difference 
may  not  be  great,  but  we  might  as  well  use  the  accurate 
figures,  especially  when  it  is  no  more  trouble. 

9.  Steam  or  Power  Used  Auxiliary  to  the  Production 
of  Steam. — One  of  the  most  serious  defects  in  both  the 
American  "  Mechanicals  "  and  the  "  Civils  "  Codes  is  the  scanty 
attention  given  to  the  question  of  steam  or  power  used 
auxiliary  to  the  production  of  steam,  arid  this  fact  alone  largely 
destroys  the  real  value  of  any  boiler  plant  test  carried  out 
according  to  either  of  the  codes.  To  illustrate  this  point,  it  is 
best  to  start  with  the  simplest  possible  boiler  plant,  namely, 
one  boiler,  hand-fired,  with  injector  feed  and  natural  chimney 
draught.  Apart  from  the  infinitesimal  amount  of  heat  taken 
as  energy  in  working  the  injector  (the  latent  heat  of  the  steam 
used  being  returned  to  the  boiler)  all  the  steam  produced 
from  this  boiler  is  useful  steam  ready  for  the  factory.  That 
is,  if  5000  Ibs.  of  water  is  evaporated  per  hour,  5000  Ibs.  of 
steam  is  ready  at  the  boiler  stop  valve  for  useful  work,  and 
the  real  net  working  efficiency  of  the  plant  is  calculated  on 
this  5000  Ibs.  evaporation. 

But  if  we  now  add  to  this  simple  boiler  plant  any  appliance 
to  help  in  generating  the  steam,  and  this  appliance  takes  some 
steam  directly  or  indirectly  to  work  it,  then  this  latter  steam 
must  be  deducted  from  the  evaporation  in  calculating  the 
real  net  working  efficiency  of  the  plant. 

For  example,  if  a  steam  jet  furnace,  hand  or  mechanically 
fired  is  added  to  the  plant,  and  the  amount  of  steam  taken  by 
the  steam  nozzles  is  10  per  cent,  of  the  production  of  the 


CRITICISMS  OF  EXISTING  CODES  95 

boiler,  that  is,  500  Ibs.  per  hour,  then  the  real  net  production 
of  the  boiler  plant  is  only  4500  Ibs.  useful  steam  per  hour 
(5000  -  500)  in  spite  of  the  fact  that  the  boiler  is  still  evaporat- 
ing 5000  Ibs.  The  net  working  efficiency  must  be  calculated 
on  the  4500  Ibs.,  that  is,  the  real  amount  of  steam  available  for 
useful  work.  This  may  sound  elementary  and  obvious,  but 
it  is  at  any  rate  not  clear  to  the  Committees  who  devised  the 
two  Codes,  and  it  is  conveniently  ignored  in  practically  every 
boiler  plant  test  that  has  ever  been  published.  Thus  at  the 
present  time  we  have  firms  making  appliances  for  steam  genera- 
tion, advertising  broadcast  figures  of  tests  carried  out  with  their 
particular  appliances,  in  which  results  of  75  to  80  per  cent, 
boiler  plant  efficiency  are  shown,  and  the  fact  that  the  appli- 
ance itself  may  be  wasting  say  2-J  to  20  per  cent,  of  the  steam 
production  of  the  whole  plant  is  coolly  ignored. 

It  surely  must  be  obvious  that  all  steam  used  in  connection 
with  the  production  of  the  steam  must  be  deducted,  and  from 
the  point  of  view  of  real  net  working  efficiency  the  boiler 
plant  must  be  regarded  as  being  in  a  closed  box,  into  which 
a  certain  amount  of  heat  as  coal  or  other  fuel  is  thrown  at  one 
end,  and  a  certain  lesser  amount  of  heat  as  useful  steam  comes 
out  at  the  other  end,  as  shown  in  Figs.  15  and  16. 

The  references  given  to  this  vital  point  in  the  "  Civils  " 
Code  are  so  confusing  that  one  can  only  say  that  no  definite 
instructions  are  given  at  all.  These  references  dissected  from 
the  Code  are  as  follows  (p.  7)  : — 

"  It  is  particularly  desirable  that  arrangements  should 
be  made  for  supplying  the  steam  used  by  auxiliary  apparatus, 
such  as  steam  blast,  fans,  pumps,  etc.,  from  a  separate 
boiler  entirely  disconnected  from  that  under  trial,1  separate 
feed-measuring  apparatus  being  provided  if  it  is  desired  to 
ascertain  the  quantity  of  steam  thus  used.  If  such  auxiliary 
boiler  cannot  be  blanked  off  during  the  trial,  the  pressure  in  it 
should,  if  possible,  be  maintained  the  same  as  that  in  the 
boilers  under  trial,  in  order  to  minimise  leakage  through  the 
stop- valve  ". 


96 


BOILER  PLANT  TESTING 


CRITICISMS  OF  EXISTING  CODES 


97 


98  BOILER  PLANT  TESTING 

The  above  note l  refers  to  page  70,  and  is  as  follows  : — 

"  No.  30.  Steam  Used  by  Steam  Jets  and  Fans. — 
Many  mechanical  stokers  are  provided  with  steam  jets 
under  the  bars,  others  require  steam  for  actuating  the 
mechanism  of  the  fans.  The  ^necessary  steam  may,  under 
special  conditions,  exceed  10  per  cent,  of  the  quantity  pro- 
duced, and  should  be  subtracted  from  the  weight  of  feed-water 
(unless  the  efficiency  of  the  heating  surface,  is  in  question) 
because  it  is  not  available  for  useful  work  ". 

There  is  also  the  following  : — 

Page  74,  paragraph  "  Line  3  ".  "  If  mechanical  stokers  are 
used,  the  name  of  the  stoker  should  be  stated,  and  also  whether 
it  was  of  the  sprinkling  or  coking  type,  unless  the  information 
has  already  been  given  in  Line  i.  It  is  desired,  if  possible,  to 
give  particulars  of  the  power  needed  to  work  the  stoker  and 
how  supplied." 

Page  74,  paragraph  "  Line  4  ".  "  If  any  system  of  forced  or 
induced  draught  is  used  it  should  be  carefully  explained,  and 
the  positions  and  any  peculiarities  of  the  draught  gauges  be 
described  :  data  as  to  the  power  needed  or  steam  used  should 
be  supplied,  if  possible." 

Page  78  "Line  30".  " Wherever  possible  the  amount  of 
steam  employed  in  producing  the  draught  (whether  an  actual 
steam  jet  is  used  or  whether  the  steam  is  used  in  working  an 
engine  for  driving  fans)  should  be  given,  and  it  should  be 
determined  by  an  independent  test.  The  steam  which  is 
blown  through  nozzles,  can,  however,  with  a  reasonable  degree 
of  accuracy,  be  calculated  by  the  formula  on  page  71  (Sect.  30)." 

It  is  obvious,  therefore,  that  the  "  Civils  "  Code  in  general 
regards  the  determination  of  the  steam  or  power  used  as  of 
little  or  no  value,  although  "  it  is  desirable  if  possible "  to 
undertake  it.  In  fact,  so  little  importance  do  they  attach  to 
this  question  that  they  do  not  even  trouble  in  the  calculations 
to  give  an  example,  although  a  number  of  pages  are  devoted 
to  explaining  how  to  calculate  a  "heat  balance  sheet"  from 
the  flue  gas  analysis,  a  matter  of  relatively  little  moment. 
Thus  also  on  page  5  it  is  stated  that : — 


CRITICISMS  OF  EXISTING  CODES  99 

"  The  principal  measurements  are  those  pertaining  to  the 
weighing  of  the  fuel  and  the  determination  of  its  quality  ;  to 
the  weighing  of  the  water  evaporated,  and  to  the  measure- 
ment of  the  power  produced.  The  data  thus  obtained  suffice 
to  determine  the  thermal  efficiency  of  a  boiler." 

In  the  American  "  Mechanicals  "  Code  the  following 
appears  (p.  47,  § 


"  Correction  for  Steam  or  Power  Used  for  Aiding 
Combustion.  —  The  quantity  of  steam  or  power,  if  any 
used  for  producing  draught,  injecting  fuel,  or  aiding  com- 
bustion, should  be  determined  and  recorded  in  the  Table 
of  Data  and  Results.  This  should  also  be  recorded  by  foot- 
note below  the  table,  a  statement  showing  whether  or  not  a 
deduction  has  been  mide  from  the  total  evaporation  for  steam 
or  power  so  used,  and  if  such  deduction  has  been  made,  the 
method  of  computing  it." 

The  American  Code,  therefore,  only  considers  auxiliary 
steam  or  power  as  a  matter  for  a  foot-note,  and  leaves  it 
apparently  to  the  fancy  of  the  engineers  in  charge  as  to 
whether  they  bother  to  deduct  it  or  not. 

The  various  points  of  the  plant,  where  such  auxiliary 
steam  or  power  is  used  (already  given  in  Figs.  15-16),  con- 
sidered in  detail,  are  as  follows  ;  — 

(1)  Mechanical  Coal  and  Ash    Handling.  —  The    amount 
of  steam  or  power  taken  here  is  not  excessive.      An  average 
sized  plant  of  three  "  Lancashire  "  boilers  handling,  say,  90*0 
tons  of  coal   per  week    will    take  approximately,  say,  3  h.p. 
reckoned  as  continuous  working.      The  determination  of  the 
h.p.  and  its  equivalent  in  steam  production  on  the  plant,  can 
be  determined  without    trouble.     Thus,  if  a  small  non-con- 
densing steam  engine  is  used,  the  figure  of  30  Ibs.  of  steam 
per  i.h.p.  can  be  taken,  and  the  h.p.  of  the  engine  calculated 
in  the  ordinary  way.     Such  a  result  will  be  accurate  to  10 
per  cent,  which  is  near  enough  as  this  particular  item  is  only 
a  small  one. 

(2)  Mechanical  Stoker  or  Moving  Hand-fired  Bar  Drive.  — 
Here  again,  the  power  is  not  particularly  excessive,  averaging 


ioo  BOILER  PLANT  TESTING 

I  to  2  h.p.  per  boiler  in  most  cases,  say  30  to  60  Ibs.  of 
steam  per  boiler  per  hour,  or  0-4  to  O'8  per  cent  of  the  pro- 
duction, and  can  be  calculated  as  in  item  (i). 

(3)  Steam  Jets. — The  question  of  steam  jets  is  undoubtedly 
the  worst  feature  of  this  question  of  auxiliary  steam,  and  the 
"  Civils  "  Code  does  not  realise  the  importance  of  it.  It  ad- 
mits in  one  paragraph  that  the  amount  may  be  10  per  cent 
of  the  production,  and  then  in  another,  contents  itself  with  a 
pious  expression  that  the  amount  should  be  determined  if 
possible.  There  is  not  the  slightest  indication  given  that  it 
is  just  as  essential  to  determine  this  figure  as  it  is  that  of  the 
amount  of  water  evaporated  and  the  coal  burnt,  and  that 
without  the  figure  any  boiler  test  is  practically  useless. 

As  further  showing  the  minor  importance  attached  to  this 
point  by  the  "  Civils"  Code  we  have  the  following  (p.  71)  :— 

"  The  steam  which  is  blown  through  nozzles  can,  with 
a  reasonable  amount  of  accuracy,  be  calculated  with  the 
help  of  the  formula  : — 

Q  -  Ibs.  of  steam  per  minute  =  P  x  a 

where  P  =  the  steam  pressure  above  that  of  the  atmosphere 
(i.e.  it  is  the  gauge  pressure)  plus  7-5  Ibs. 

and  a  is  the  sectional  area  in  square  inches  of  all  the  nozzles. 
This  formula  gives  too  high  results  for  pressure  below  50  Ibs. 
per  square  inch.  P  should  be  measured  near  the  nozzles. 
If  the  steam  is  superheated,  the  weight  of  steam,  as  found 
above,  must  be  multiplied  by  the  square  root  of  the  ratio  of 
the  absolute  temperatures  (t  +  459)  of  the  saturated  and 
superheated  steam." 

I  maintain  that  such  an  empirical  formula  is  absolutely 
worthless  for  determining  the  real  amount  of  steam  used  by 
nozzles. 

In  the  first  place,  it  is  impossible  to  determine  with  any 
reasonable  amount  of  accuracy  the  area  of  a  number  of  nozzles. 
For  example,  a  given  steam  jet  furnace  may  have  anything 
from  6  to  64  nozzles  per  boiler,  and  these  nozzles  soon  wear 
larger  by  the  friction  of  the  steam,  the  holes  being  then,  as  a 


CRITICISMS  OF 

rule,  irregular  in  shape.  It  is  a  hopeless  job,  under  these  con- 
ditions, on  an  average  sized  boiler  plant  of,  say,  four  boilers, 
with  anything  from  100  to  200  nozzles,  to  get  the  real  area 
of  all  these  nozzles. 

I  once  tested  a  boiler  plant  of  thirty-two  "Lancashire" 
boilers  with  14  nozzles  per  boiler,  that  is,  a  total  of  448 
nozzles  on  the  plant,  and  the  "  Civils  "  Code  seriously  suggests 
that  the  only  way  in  testing  this  plant  would  be  to  try  and 
measure  the  irregular  area  of  448  different  nozzles  worn  by 
the  steam,  each  nozzle  having  to  be  taken  off  by  means  of 
pliers,  and  then  replaced.  Also,  such  nozzles  are  supplied  as 
a  rule  from  each  boiler  independently  by  a  small  steam  pipe, 
which  may  be  -J  to  I  in.  in  diameter,  and  this  pipe  is  provided 
with  a  stop-valve  which  is  often  worked  partially  open,  so  that 
the  actual  area  of  the  nozzles  is  in  any  case  not  a  criterion  of 
the  amount  of  steam  passing. 

The  American  "  Mechanicals  "  Code  recommends  the  use 
of  steam  meters,  but  allows  also  various  empirical  methods, 
as  given  below  (p.  1 3) : — 

9<r.  Steam  Measuring  Apparatus. — Various  forms  of  steam 
meters  may  be  employed  for  measuring  steam,  provided 
such  meters  are  properly  calibrated  under  conditions  of  use, 
and  the  pulsations  of  pressure,  if  any,  are  not  serious.  For 
measuring  the  steam  used  by  the  auxiliaries  of  a  steam 
plant,  either  individually  or  collectively,  the  orifice  form  of 
steam  meter  may  be  used,  consisting  of  an  orifice  in  a  plate 
inserted  between  the  two  halves  of  a  pair  of  flanges  in  the 
pipe  through  which  the  steam  passes,  or  placed  in  a  bye-pass 
through  which  the  steam  is  diverted,  with  gage  pipe  on  either 
side  for  determining  the  fall  of  pressure.  The  quantity  of 
steam  represented  by  the  various  differences  of  pressure  which 
occur,  may  be  found  by  arranging  the  apparatus  so  as  to  draw 
steam  through  the  orifice,  and  discharge  it  into  a  tank  of 
water  resting  on  platform  scales,  by  which  its  actual  weight 
in  a  given  time  is  determined. 

"  A  plate  \  in.  thick  containing  an  orifice  I  in.  diameter, 
with  square  edges,  will  discharge  the  approximate  quantities 
of  dry  steam  per  hour  given  in  Table  L,  with  various  pressure 
drops,  the  pressure  below  the  orifice  being  100  Ibs.  by  gage. 


iQ2\l  <?\  >'l  V 


PLANT  TESTING 


Lbs.  of 
Dry  Steam 
Per  Hour. 

;''  • 

430 

615 

" 

930 
I2OO 

1400 
1560 
2180 

.  '  •  ., 

'ffc  . 

2640 

3050 

TABLE  I. — DISCHARGE  THROUGH  ORIFICE  i  IN.  DIA.  AT  100  LBS.  PRESSURE. 

Pressure 
Drop,  Lbs. 
Per  Sq.  In. 

4 

I 

2 
3 

4 

5 

10 

15 
20 

"The  water-glass  method  affords  an  approximate  means 
for  determining  the  steam  consumption  of  auxiliaries,  and  for 
measuring  the  leakages  of  steam  and  water  from  the  boiler 
and  its  connections.  (See  Appendix  No.  3  for  description  of 
water-glass  method.)" 

The  empirical  "water-glass"  (i.e.,  gauge  glass)  method 
is  described  as  follows  (p.  154)  : — 

*'(£)  Water-Glass  Tests  of  Leakage.  —  224.  To  deter- 
mine the  leakage  of  steam  and  water  from  a  boiler  and 
steam  pipes,  etc.,  the  water-glass  method  may  be  satisfac- 
torily employed.  This  consists  of  shutting  off  all  the  feed 
valves  (which  must  be  known  to  be  tight)  and  the  main  feed 
valve,  thereby  stopping  absolutely  the  entrance  or  exit  of 
water  at  the  feed  pipes  to  the  boiler  ;  then  maintaining  the 
steam  pressure  (by  means  of  a  very  slow  fire)  at  a  fixed  point, 
which  is  approximately  that  of  the  working  pressure,  and  ob- 
serving the  rate  at  which  the  water  falls  in  the  gage  glasses. 
It  is  well,  in  this  test,  as  in  other  work  of  this  character,  to 
make  observations  every  ten  minutes,  and  to  continue  them 
for  such  length  of  time  that  the  differences  between  successive 
readings  attain  a  constant  rate.  In  many  cases  the  conditions 
will  have  become  constant  at  the  expiration  of  fifteen  minutes 
from  the  time  of  shutting  the  valves,  and  thereafter  the  fall  of 
water  due  to  leakage  of  steam  and  water  become  approxi- 
mately constant.  It  is  usually  sufficient,  after  this  time,  to 
continue  the  test  for  two  hours,  thereby  obtaining  a  number 
of  half-hourly  periods.  When  this  test  is  finished,  the  quantity 
of  leakage  is  ascertained  by  calculating  the  volume  of  water 
which  has  disappeared,  using  the  area  of  the  water  level  and 
the  depth  shown  on  the  glass,  making  due  allowance  for  the 
weight  of  one  cubic  foot  of  water  at  the  observed  pressure." 


CRITICISMS  OF  EXISTING  CODES  103 

The  vital  importance  of  a  proper  method  of  determining 
the  steam  used  by  the  nozzles  is  best  shown  by  giving  some 
indication  of  the  amount  of  steam  that  is  being  used  by  them 
in  practice. 

I  have  already  given  (p.  45)  some  data  on  this  point, 
and  in  my  experience,  the  average  consumption  is  about 
6 -5  per  cent,  of  the  evaporation  of  the  plant.  Of  the 
400  plants  tested,  153,  that  is  38  per  cent,  were  fitted  with 
steam  nozzles,  and  the  figures  for  each  of  these  153  tests  are 
given  in  the  columns  of  figures  on  pages  104-7. 

With  regard  to  the  method  to  be  used  for  determining  the 
amount  of  steam  used  by  steam  jets,  in  the  International  Code 
I  suggest  the  alternatives  of  a  steam  meter,  or  a  surface 
condenser. 

The  only  matter  for  criticism  on  this  point  in  the 
American  J<  Mechanicals"  Code  is  that  it  does  not  make  the 
use  of  steam  meters  compulsory,  and  allows  alternative  em- 
pirical methods,  but  the  "  Civils  "  Code  does  noj:  allow  steam 
meters  at  all.  Steam  meters  will  be  dealt  with  more  par- 
ticularly on  page  131,  but  they  are  especially  convenient  for 
determining  with  great  accuracy  (say  to  I  per  cent  since  the 
demand  is  steady)  the  amount  of  steam  used  by  nozzles,  when 
these  nozzles  are  all  fed  from  one  main  supply  pipe. 

I  would  recommend  strongly,  as  the  ideal  arrangement  for 
a  modern  boiler  plant,  that  the  steam  pipes  be  so  designed 
that  the  whole  of  the  auxiliary  steam  of  the  plant  be  passed 
through  one  auxiliary  steam  main  pipe,  as  a  branch  from  the 
main  steam  pipe  over  the  boilers.  On  this  auxiliary  pipe 
should  be  installed  a  steam  meter,  ^which  would  thus  give  a 
continuous  record  of  all  the  auxiliary  steam.  Also,  because 
the  amount  used  by  steam  nozzles  is  much  the  greatest  and 
requires  special  watching,  I  would  recommend  further  that  all 
these  nozzles  be  supplied  by  one  pipe  branching  from  this 
auxiliary  steam  main  pipe,  and  on  this  pipe  a  second  steam 
meter  be  installed. 


IO4 


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CRITICISMS  OF  EXISTING  CODES 


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For  ordinary  testing  purposes  the  objection  to  the  steam 
meter  is  that  the  steam  nozzles  are  almost  always  supplied  by 
a  separate  small  pipe  from  each  boiler,  a  most  wasteful  and 
unscientific  method,  which  makes  it  difficult  to  determine  the 
amount  of  steam  used.  Consequently,  even  if  only  two  or  three 
boilers  are  tested,  the  steam  meter  has  to  be  coupled  up  to 
each  boiler  in  turn,  a  very  troublesome  proceeding,  although 
when  once  connected,  this  method  is  decidedly  the  best.  In 
testing  the  400  boiler  plants,  I  have  used  the  surface  condenser 
method,  and  have  devised  for  the  purpose  the  apparatus 
illustrated  in  Fig.  17,  and  in  the  photograph  of  Fig.  18. 

This  apparatus  has  been  in  use  for  many  years,  and  found 
to  be  most  satisfactory. 

In   Fig.    17,  A  is   a  sheet-iron  cylinder,   water-jacketted, 


io8 


BOILER  PLANT  TESTING 


with  bolted  lid  B.     The  steam  jet  appliance,  nozzles,  pipes, 
etc.,   is  detached  from  the    furnaces    of  say  one  boiler,   and 


placed  bodily  inside  the  cylinder  A,  being  attached  by  a  short 
pipe  to  coupling  a,  b,  cy  d,  as  most  convenient,  in  the  lid  B. 
The  steam  jets  are  then  connected  to  the  boiler,  the  whole 


CRITICISMS  OF  EXISTING  CODES  109 

apparatus  being  stood  in  the  firehole  close  up  against  the 
boiler,  so  that  the  steam  is  blowing  through  the  nozzles  in  the 
cylinder  A  exactly  as  it  does  when  attached  to  the  boiler 
furnace.  The  steam  then  blows  down  through  the  pipe  C 
and  through  the  coil  D,  open  to  the  air  at  E.  A  con- 
tinuous flow  of  cold  water  enters  the  jacket  'by  the  pipe  F 
and  leaves  by  the  pipe  G,  and  then  flows  into  the  large 
cooling  vessel  H.  As  a  consequence  the  steam  from  the 
nozzles  is  condensed,  and  runs  out  at  E,  where  it  is  weighed. 

In  working  the  apparatus,  the  valve  on  the  steam  supply 
to  the  nozzles  is  opened  the  same  as  usual,  and  as  soon  as  a 
steady  stream  of  condensed  water  is  issuing  from  E,  the  test 
is  carried  out  at  half-hourly  intervals  by  putting  under  the 
flow  at  E  a  weighed  bucket  at  the  half-hour  by  the  clock, 
and  collecting  all  the  condensed  water  for  weighing  until  the 
next  half-hour.  In  this  way  numerous  tests  can  be  carried 
out,  under  any  different  conditions  as  regards  the  amount  of 
turn  of  the  steam  supply  valve,  boiler  pressure,  etc. 

One  method  (which  is  not  to  be  recommended)  that  has 
been  used  to  determine  the  amount  of  steam  used  by  the 
nozzles  is  to  place  the  nozzles  in  a  weighed  amount  of  cold 
water,  and  to  pass  in  the  steam  for  a  given  time,  so  that  the 
water  does  not  get  hot  enough  to  lose  weight  by  giving  off 
steam.  The  increase  in  weight  then  represents  the  amount 
of  steam  passed  by  the  nozzles,  but  there  is  some  difference  of 
opinion  as  to  whether  the  same  amount  of  steam  issues  from 
the  nozzles  in  the  air  under  the  furnace  as  it  does  when 
immersed  in  cold  water. 

The  "  Civils  "  Code  also  mentions  the  method  of  having 
one  separate  boiler  devoted  to  supplying  only  the  steam 
nozzles,  and  measuring  the  amount  of  water  evaporated  in 
this  boiler  to  determine  the  steam  produced.  This,  in  my 
opinion,  is  not  only  quite  unnecessary,  but  means  also  in  most 
cases  altering  all  the  pipe  circuits  for  the  steam  nozzles,  as 
already  described.  If  we  are  going  to  go  to  all  this  trouble, 
the  steam  meter  is  obviously  the  best  method.  Further,  it 


i  io  BOILER  PLANT  TESTING 

must  be  remembered  that  the  efficiency  of  the  auxiliary  boiler 
plant  may  be  different. 

(4)  Mechanical  Draught. — This  is  also  an  important  item, 
as    mechanical    draught   may  take    anything   from   say    I   to 
3  per  cent,  of  the  production.   /The  typical    installation   of 
induced  draught   driven    by  direct  coupled  high-speed  non- 
condensing   engine    absorbs  about  6  h.p.   per  "  Lancashire " 
boiler,   30    x  8   ft,   and    the   consumption  of  the   engine  is 
about    35    Ibs.    of    steam     per    i.h.p.,    corresponding    to    an 
evaporation  of  215  Ibs.  per  hour,  or  say,  in  averages,  2*75  Per 
cent,    of  the   production.       In    most    cases    it  is  sufficiently 
accurate  to  calculate  the  i.h.p.   of  the  engine  under  average 
conditions  in  the  ordinary  way,  but  in  special  cases  the  actual 
steam    consumption    can    be   determined  by  condensing  the 
exhaust  steam  or  by  a  steam  meter.      If  the  exhaust  steam  is 
used  to  heat  the  feed-water,  this  heat  added  to  the  plant  must 
of  course  be  deducted  in  calculating  the  steam  taken  by  the 
engine.     When  the  fan  is  electric  driven,  the  power  can  of 
course  be  obtained  easily,  but  it  must  be  calculated  back  to 
steam  production  of  the  plant,  as  if  the  current  was  generated 
on  the  spot.      If  the  current  is  purchased  from  outside  sources 
the  cost  must  be  calculated  in  the  terms  of  coal. 

It  is  very  difficult  to  get  the  figure  for  the  h.p.  when  the 
fan  is  driven  from  a  line  shaft,  a  bad  practice  in  any  case,  and 
often  the  only  way  is  by  taking  all  the  details  of  the  fan, 
revolutions  per  minute,  size,  etc.,  and  obtaining  the  h.p.  from 
a  similar  fan  driven  by  steam  engine  or  motor. 

(5)  Various  Other  Uses  of  Auxiliary  Steam. — There  are 
various  other  points  at  which  auxiliary  steam  or  power  may 
be  used,  such  as  the  boiler  feed  pumps,  economiser  scraper 
engine,  water-softening   plant,  electrolytic  processes  for   the 
prevention  of  corrosion,  and  so  on,  and  in  each  case  the  actual 
steam  taken  can  be  calculated  without  trouble  on  the  same 
general  lines,   and   added   to  the   total   amount   of  auxiliary 
steam.      As  will  be  seen,  all  these  items  added  up  together 
make  a  very  formidable  figure,  and  place  an  entirely  different 


CRITICISMS  OF  EXISTING  CODES  in 

complexion  on  the  figures  for  the  real  net  working  efficiency 
of  a  boiler  plant. 

10.  Lbs.  of  Water  from  and  at  212°  F.  per  1,000,000 
B.Th.U. — Both  Codes  give  the  figure  for  the  Ibs.  of  water  per 
Ib.  of  coal,  and  also  the  Ibs.  of  water  "  from  and  at  212°  F." 
per  Ib.  of  coal.     This  is,  however,  not  sufficient,  and  I  suggest 
to  be  included  in  the  International  Code  a  new  and  additional 
figure,  namely,  Ibs.  of  water  from  and  at  212°  F.  per  1,000,000 
B.  Th.  U.     It  is  of  course  little  use  to  give  merely  the  figure  of 
Ibs.  of  water  evaporated  per  Ib.  of  coal,  since  the  temperature 
of  the  feed- water  going  into  the  plant  may  be  at  a  temperature 
of  anything  from  32°  to  212°  F.,  and  each   11°  F.,   means  a 
difference  of  approximately  I  per  cent  in  the  coal  bill.      Both 
Codes  get  over  this  difficulty  by  calculating  the  evaporation 
"from   and  at  212°  F.,"  that  is,  taking   the   evaporation    of 
water  per  Ib.   of  coal  if  the   feed-water  was  always  212°  F. 
This,  however,  still  leaves  untouched  the  other  and  equally 
important  error,  namely,  the  heating  value  of  the  fuel,  which 
may  vary  from  7500  to   14,500  B.Th.U.   per  Ib.     The  mere 
figure,  as  given  in  the  codes,  of  the  evaporation  "  from  and  at 
212°  F."  means,  therefore,  very  little. 

For  many  years  I  have  calculated  accordingly  the  figure 
"Ibs.  of  water  from  and  at  212°  F.  per  1,000,000  B.Th.U.," 
which  obviates  both  these  difficulties,  and  I  suggest  that  this 
new  figure  be  included  in  the  International  Code. 

1 1 .  Various  Minor  Points.— 

(a)  Both  Codes  insist  upon  reading  the  barometer  during 
a  boiler  trial,  so  as  to  get  the  absolute  steam  pressure.  Thus 
in  the  "  Civils  "  Code  (p.  78,  line  34)  is  stated  :— 

"  This  (the  absolute  pressure)  is  obtained  by  adding  the 
atmospheric  pressure  to  the  gauge  pressure." 

It  seems  to  me  to  be  a  waste  of  time  to  read  the  baro- 
meter, and  for  all  the  difference  it  makes  in  the  calculations, 
the  absolute  pressure  may  just  as  well  be  taken  as  15  Ibs. 
plus  the  gauge  pressure.  It  certainly  seems  curious  for  the 
"  Civils  "  Code  to  insist  on  including  barometer  readings,  and 


ii2  BOILER  PLANT  TESTING 

yet  at  the  same  time,  as  already  seen,  taking  an  arbitrary 
figure  of  0*48  for  the  specific  of  superheated  steam,  irrespective 
of  its  temperature. 

(b)  The  new  figure  for  the  latent  heat  of  steam  is  970-8, 
which  is  included  in  the  American  "  Mechanicals  "  Code.     In 
the  "  Civils  "  Code,  however,  the  old  figure  of  966  is  used  as 
follows  (p.  86)  :— 

"  Line  48  is  line  47  multiplied  by  the  evaporation  factor, 
and  the  evaporation  factor  is  equal  to  the  total  heat  required 
to  evaporate  a  pound  of  steam  under  boiler  conditions, 

divided  by  966,  />.,  it  is  equal  to      1  ^  °." 

In  the  International  Code  970 '8  should  be  adopted. 

(c)  As    regards    temperature     measurements    ("  Civils " 
Code,  pp.  64-67),  it  is  not  necessary  to  fill  the  sockets  with 
mercury,  as  thick  oil  will  do  just  as  well  up  to  500°  to  600°  F., 
and  it  is  not  v«ry  convenient  to  take  flue  gas  temperatures  up 
to  600°  F.  with  mercurial  thermometers,  if  only  because  these 
are  so  fragile,  even  when  in  armoured  cases.     In  the  Inter- 
national Code  I  would  suggest  a  list  being  given  of  approved 
resistance  and    thermo-electric  pyrometers,   which  are  much 
more  suitable  for  boiler  testing  work. 

(d)  The  "  Civils  "   Code  (p.  37)  recommends  a  most  re- 
markable implement  as  an  aid  to  boiler  plant  testing,  namely, 
"  a  tool  (Fig.  19)  for  gauging  the  thickness  of  the  fire  in  the 
grate,"  illustrated  as  follows  : — 


FIG.  19. 
(Fig.  2  of  the  "  Civils  "  Code.) 


CRITICISMS  OF  EXISTING  CODES  113 

The  Committee  who  drew  up  the  "  Civils  "  Code  seem  to 
have  been  much  worried  as  to  possible  inaccuracies  due  to 
different  amounts  of  coal  being  in  the  fires,  at  the  commence- 
ment and  at  the  end  of  the  test.  It  is  quite  possible,  of  course, 
if  a  boiler  fire  is  filled  up  with  coal  at  the  beginning  of  the  trial, 
and  allowed  to  burn  empty  at  the  end,  that  a  considerable  error 
—  several  cvvts.  of  coal  per  "  Lancashire  "  boiler  —  will  creep  in, 
and  the  plant  will  appear  to  be  doing  better  than  is  actually 
the  case.  The  solution  of  this  difficulty  is,  however,  merely 
the  elementary  one  of  looking  at  the  fires  when  commencing, 
and  having  them  the  same  at  the  end,  and  anyone  with  any 
common  sense  at  all  will  not  be  in  error  more  than  say  I  cwt, 
equal  to  about  0*5  per  cent,  on  the  weight  of  the  coal.  It  is 
quite  easy  to  have  an  error  as  large  as  this  in  merely  weighing 
the  coal.  Such  simple  methods,  however,  will  not  do  for  the 
"  Civils  "  Code,  even  if  the  fact  that  10  to  20  per  cent,  of  the 
steam  produced  by  the  plant  being  blown  away  by  steam 
nozzles  is  regarded  as  of  no  importance. 

On  page  9  of  the  Code  we  have  :  — 

"  In  most  cases  the  principal  observer  will  be  able  to 
measure  the  thickness  of  fuel  to  within  I  in.  As  the  error 
may  be  in  opposite  senses  at  the  beginning  and  ending  of  a 
trial,  it  may  amount  to  the  weight  of  a  layer  of  fuel  2  ins. 
thick.  If  C  is  the  weight  of  green  coal,  which  will  form  I  cub. 
ft.  of  incandescent  fuel,  the  total  error  should  not  exceed 

C  x  A  x  -  -  =    -    -  Ibs.     Therefore  if  W  is  the  number  of 
12         6 

Ibs.  of  fuel  per  hour,  A  the  square  feet  of  grate  covered  by 
fuel,  when  its  thickness  is  measured,  and  n  the  percentage  of 

looCA 
error  admissible,  the  trial  must  last  hours.      C  may 


be  taken  as  20  Ibs.  for  large  coal  and  30  Ibs.  for  small  slack. 
In  making  use  of  this  formula,  however,  it  is  necessary  to  have 
some  regard  to  the  quality  as  well  as  the  size  of  the  fuel. 
When  it  contains  much  dirt  or  makes  a  pasty  clinker,  the  bars, 
if  not  self-cleaning,  have  to  be  cleaned  at  short  intervals  by 
the  firemen,  and  at  each  cleaning  there  is  loss  of  heat  and 
combustible  matter.  The  duration  of  the  trial  and  the  times 


ii4  BOILER  PLANT  TESTING 

of  cleaning  should  therefore  be  so  arranged  as  to  give  this  loss 
the  same  average  value  that  it  would  have  if  the  trial  were  in- 
definitely prolonged.  For  instance,  if  the  fuel  were  such  as  to 
make  cleaning  necessary  every  4  hours,  it  would  be  unfair  to 
make  a  5-hours'  trial.;  8  hours  would  be  the  proper  time  ;  or, 
if  it  were  not  possible  to  have  the  trial  longer  than  5  hours,  a 
more  accurate  result  would  be  obtained  by  working  for  4  hours 
only  and  cleaning  the  fire-grates  only  once." 

Accordingly,  we  are  recommended  to  use  a  "  tool,"  a  huge 
steel  poker,    i  to  i-J-  in.  diameter,  and  presumably  8  or  9    ft. 
long,  as  illustrated  in  Fig.  19.      When  the  trial  starts  we  have 
apparently  (p.  13)  to  open  the  fire-doors,  and  in  the  blinding 
heat,   rummage   about   in   each   fire   taking   the    thickness  at 
various  places,  and  recording  the  same.     This  procedure  is 
to    be  repeated   at   the  end  of  the   trial,  and  presumably  a 
calculation  made  for  different  thicknesses  of  the  fires  before 
and  after.      It  is  not  stated  whether  another  calculation  will 
also  have  to  be  made  to  compensate  for  the  loss  of  efficiency 
caused  by  having  the  fire-doors  open  and  allowing  cold  air 
to  enter  whilst  the  measurement  is  in  progress.     Taking,  for 
example,  the  case  already  mentioned,  of  a  plant  of  thirty-two 
"  Lancashire "  boilers,  do  we  understand    that    before    com- 
mencing a  test,  which  can  be  of  3  hours'  duration  ("  Civils  " 
Code,  p.  9),  it  is  necessary  to  insert  this  "  tool "  in  sixty-four 
different  furnaces  ?     I  should  estimate  that  each  determination 
would  take  at  least  4  minutes,  and  that  after  about  four  fur- 
naces one  man  would  be  exhausted,  so  that  with  relays  of 
men,  the  measurement  of  the  thickness  of  the  sixty-four  fires 
would  take,  say,  4  to  5  hours,  or  longer  than  the  duration  of 
the  test  allowed.     Or  perhaps  we  have  in  such  cases  to  have 
a  whole  battery  of  "  tools  ".     It  would  be  very  interesting  to 
know  if  any  member  of  the  "  Civils"  Committee  has   ever 
tried    to   measure   the  thickness   of  a  fire   with   the   "  tool," 
which  he  joins  in  recommending  for  this  purpose. 

(i)  On  page  7  of  the  "  Civils  "  Code  there  is  stated  : — 

"  If  it  is  desired  to  ascertain  whether  cold  water  is  lodging 
in  the  bottom  of  Lancashire  or  other  boilers  of  similar  type,  a 


CRITICISMS  OF  EXISTING  CODES  115 

horizontal  tube  should  be  screwed  into  the  front  part  of  the 
boiler,  or  preferably  the  front  manhole  door.  The  stopped 
end  of  the  tube  should  be  carried  sufficiently  far  back  to 
avoid  the  possible  lodgment  of  cool  water  at  the  front  end 
which  may  arise  from  the  bottom  flue  not  extending  right  up 
to  the  front  of  the  boiler." 

What  this  means  is  not  clear. 

12.  The  Method  of  Calculating  the  Results.— The 
methods  given  in  both  the  Codes  for  calculating  the  results  of 
a  boiler  test  are,  in  general,  so  completely  involved  and  com- 
plicated, that  it  is  impossible  to  criticise  them  in  detail  in  any 
reasonable  length.  It  seems  to  me  that  the  fundamental  error 
in  these  methods  is  the  attempt  at  all  costs  to  evolve  a  "  heat 
balance  sheet,"  which,  in  my  opinion,  is  not  necessary,  and  in 
any  case  is  inaccurate. 

In  dealing  with  this  difficult  subject,  I  propose,  for  the 
sake  of  simplicity,  to  describe  first  the  method  of  calculation 
which  I  suggest  be  embodied  in  the  International  Code.  I 
hope  to  show  that  this  method  is  quite  simple  and  practical, 
that  there  is  no  particular  mathematical  knowledge  required  at 
all,  and  that  the  complete  figures  of  an  official  trial  can  be 
worked  out  in  twenty  minutes  on  first  principles  without  any 
empirical  formulae.  In  this  connection  the  "  Civils "  Code 
especially  falls  into  the  error  of  giving  ready-made  formulae 
and  symbols,  which  means  that  most  engineers  use  these  in  a 
rule-of-thumb  way  without  understanding  the  principles  in- 
volved, and  errors  are  bound  to  result. 

Taking  again  the  specimen  test  results  on  page  146,  the  es- 
sential figures,  apart  from  simple  averaging,  division,  etc.,  which 
require  no  consideration,  are  that  105,328  Ibs.  of  water  at  I2I°F. 
are  evaporated  on  the  plant,  the  average  temperature  after  the 
economiser  being  296°  F.  and  the  temperature  of  the  super- 
heated steam  averaging  475°  F.  with  147  Ibs.  gauge  pressure 
(162  Ibs.  absolute).  At  the  same  time  15,960  Ibs.  of  coal 
with  a  net  calculated  heating  value  of  11,715  B.Th.U.  per 
Ib.  are  burnt,  and  the  total  amount  of  auxiliary  steam  (or 
power  expressed  as  steam)  is  13,639-9  Ibs.  (12-95  per  cent.). 


n6  BOILER  PLANT  TESTING 

The  essential  figure  required,  to  which  all  other  figures  are 
merely  subsidiary,  is  the  net  working  efficiency  of  the  com- 
plete steam  generation  plant,  that  is  to  say,  for  every  100  Its 
of  fuel  delivered  to  the  plant,  how  many  Ibs.  of  fuel  are 
actually  used  for  the  production  of  useful  steam,  and  how 
many  Ibs.  are  wasted.  Thus,  when  we  say  that  the  average 
net  working  efficiency  of  the  boiler  plants  of  Great  Britain  is 
60  per  cent,  we  mean  that  out  of  every  100  Ibs.  of  coal  burnt, 
60  Ibs.  are  used  to  produce  useful  steam  and  40  Ibs.  are 
wasted  in  radiation,  imperfect  combustion,  leaky  brickwork, 
loss  of  heat  in  the  ashes,  auxiliary  steam  used  on  the  boiler 
plant  itself  and  so  on.  We  have,  therefore,  in  the  calculations, 
to  determine  the  actual  number  or  British  Thermal  Units  of 
heat  given  to  the  plant  in  the  fuel,  and  the  actual  number  of 
British  Thermal  Units  of  heat  coming  out  of  the  plant  as 
useful  steam. 

By  the  steam  tables  we  find  that  the  total  heat  required  to 
convert  I  Ib.  of  water  at  32°  F.  into  steam  at  162  Ibs.  absolute  is 
1 194  5  B.Th.U.  The  feed- water  entering  the  plant  is,  however, 
121°  F.,  that  is  to  say,  less  heat  is  required  than  1194*5  to 
convert  I  Ib.  of  water  at  121°  F.  to  steam  at  162  Ibs.  absolute. 

The  "  Civils  "  Code  assumes  that  the  specific  heat  of  water 
is  the  same  at  all  temperatures,  that  is  to  say,  the  British 
Thermal  Unit  of  Heat  is  the  amount  of  heat  required  to  heat 
I  Ib.  of  water  i°  F.  irrespective  of  the  initial  temperature  of  the 
water.  Or,  in  other  words,  that  it  takes  the  same  amount  of 
heat  to  raise  the  temperature  of  I  Ib.  of  water  from,  say,  32° 
to  33°  F.  as  it  does  to  raise  it  from,  say,  200°  to  201°  F., 
and  therefore  the  amount  of  heat  required  to  convert  I  Ib.  of 
water  at  any  initial  temperature  (/)  above  32°  F.  into  steam  at 
a  given  pressure  can  be  got  by  subtracting  32  from  (/),  calling 
the  figure  B.Th.U.,  and  then  subtracting  it  from  the  total  heat 
figure  from  32°  F.  In  the  example,  therefore,  according  to 
the  "  Civils"  Code,  the  total  heat  from  121°  F.  is  121  -  32 
=  89,  subtracted  from  1194-5  =  1105-5.  This,  of  course,  is 
erroneous,  and  the  specific  heat  of  water  is  different  for  every 


CRITICISMS  OF  EXISTING  CODES 


117 


0  F.  The  heat  required  to  raise  I  Ib.  of  water  from  32°  to  33°  F. 
is  a  maximum,  and  the  specific  heat  very  slightly  falls  with 
the  temperature  to  about  130°  F.  and  then  rises  again  as 
shown  on  the  curve,  Fig.  20.  Thus,  for  the  given  example 
of  121°  F.  the  amount  of  heat  to  be  subtracted  is  not  121 
-  32  =  89  B.Th.U.,  but  actually  88  B.Th.U. 

This  is  not  of  course  a  very  serious  matter,  but  as  it  is  no 
more  trouble  to  be  accurate,  I  suggest  that  in  the  International 

r* 


I'lSo 


rioo 

SPECIFIC 
HEAT- 


I'ooo 


FIG.  20. — Curve  showing  the  specific  heat  of  water  at  different  temperatures. 

Xr 

Code  the  formula /&  =  foi/f-  35  is  used  in  calculating  the 
heat  (//)  at  a  given  temperature  (f)  to  be  subtracted  from  the 
total  heat  at  32°  F.  This  formula  is  quite  simple,  and  gives 
a  very  near  approximation  indeed  to  the  mathematical  curve. 
Thus  at  121°  F. 

h  =  (1-017  x  121°  F)  -  35 
=  123-057  -  35 
=  88  B.Th.U 

which  subtracted  from  1194-5  gives  the  figure  of  1106-5. 


ii8  BOILER  PLANT  TESTING 

In  the  same  way  for  the  economiser  calculation,  the  total 
heat  from  296°  F.  is  (296  x  1-017  -  35)  =  266-0  B.Th.U., 
so  that  the  total  heat  from  296°  F.  is  1194-5  -  266  =  928-5 
B.Th.U.  Also,  the  steam  is  superheated  to  475°  F.,  that  is 
475°  ~  364-4°  (saturation  temperature  from  the  steam  tables) 
=  1 1 06°  F.,  and  from  Knoblauch  and  Jakob's  Superheat  Tables 
the  specific  heat  of  steam  at  475°  F.  and  162  Ibs.  absolute  is 
0-54.  1 10-6  x  o  54  =  597,  so  that  the  amount  of  heat 
required  to  raise  I  Ib.  of  water  at  121°  F.  to  steam  at  162  Ibs. 
absolute,  and  superheat  it  to  475°  F.  is  11065  +  597  = 
1166-2  B.Th.U.  This  gives  us  all  the  figures  necessary  for 
the  amount  of  heat  absorbed  by  I  Ib.  of  water  under  the 
different  conditions  of  the  boiler,  economiser  and  superheater. 

In  the  test  105,328  Ibs.  of  water  required   15,960  Ibs.  of 

coal,  so  that  I  Ib.  of  water  = 5  =  0*15152   Ibs.  of  coal. 

105  320 

Also,  since  the  net  heating  value  of  I  Ib.  of  coal  is  11,715 
B.Th.U.,  0-15152  Ibs.  of  coal  will  contain  11715  x  0-15152 
—  1 775'O  B.Th.U.,  which  represents,  therefore,  the  actual  heat 
put  into  the  plant.  The  net  percentage  of  heat  taken  by  the 
different  essential  portions  of  the  plant  is  now  as  follows  : — 

(1)  Boiler  Only. — Since  the  amount  put  in  the  firehole  was 
1775-0  B.Th.U.,  and  that  absorbed    by  the  boiler  is    928-5 
B.Th.U.  (i.e.,  heating  the  water  from  296°  F.  to  saturation  at 
162  Ibs.),  the  percentage  of  heat  in  the  original  coal  absorbed 

,    928-5  x   100 
by  the  boiler  is  -  — — — =  52-31  per  cent. 

(2)  Economizers    Only. — Again,    since    the    heat    put    in 
the  firehole  is   1775-0  B.Th.U.,  and  that  abstracted    by  the 
boiler  and  economisers  is    1106-5   B.Th.U.  (i.e.,  heating  the 
water  from  I2I°F.  to  saturation  at  162  Ibs.),  the  percentage 
of  heat  absorbed  by  the  boiler  and  economiser  is 

1 106-5  x  IPO  _  62.33  per  cent 

Since  the  boiler  was  52-31  per  cent,  the  economiser  only  will 
be  62 -3  3  -  52-31  =  10-02  percent. 


CRITICISMS  OF  EXISTING  CODES  119 

(3)  Superheater     Only.  —  Again,    as    before,    taking    the 
original  figure  of  I775'O  B.Th.U.,  the    amount  of  heat  ab- 
sorbed by  the  boiler,   economiser  and  superheater  is   1  166*2 
B.Tn.U.   (i.e.,  heating  the  water  from   121°  F.   to  saturation 
at   162   Ibs.  and  superheating  to  475°  F.),  the  percentage  of 
heat  absorbed  by  the  boiler,  economiser  and  superheater  is 

1166-2  x   100 
-  -  —    -  =  65  70  per  cent.,  and    as  the  figure  for    the 

boiler  and  economiser  together  is  62-33  Per  cent.,  the  figure 
for  the  superheater  only  is  6570-  62*33  =  3-37  per  cent. 

(4)  Net    Working  Efficiency.  —  We   have    seen,    therefore, 
that  for  100  Ibs.  of  coal  put  in  the  firehole  52-31  are  absorbed 
by  the  boiler,  10-02  by  the  economiser,  and  3-37  by  the  super- 
heater, a  total  of  6570,  the  other  34*30  parts  being  wasted  by 
radiation,  inefficient  combustion,  leaky  brickwork,  etc.     This 
figure  of  6570  per  cent,  is  not,  however,  the   net  working 
efficiency  of  the  plant,  because  although  6570  per  cent,  of  the 
heat  of  the  coal  is  absorbed  by  the  boiler,  economiser  and 
superheater,  this  heat  is  not  given  out  of  the  plant   to  the 
factory  as  steam.      12-95  Per  cent-  °f  it:  *s  taken  up  by  the 
plant  itself,  as  already  seen,  for  steam  jets,  induced  draught, 
boiler  feed  pump,  etc.     The  real  net  working  of  the  plant  is 

6570  x  12-95 
therefore  -     -     -  =  8-50  -  65  70  =  57'2O  per  cent. 


(5)  From  and  at  212°  F.  Calculation.  —  In  order  to  cal- 
culate the  Ibs.  of  water  evaporated  per  Ib.  of  coal,  assuming 
the  water  was  212°  F.  (instead  of  actually  121°  F.),  all  that  is 
necessary  to  do  is  to  multiply  the  Ibs.  of  water  at  121°  F.  per 

Ib.  of  coal,  that  is,          ^-   =  6  -60  x   1106-5  (the  total  heat 

from  121°  F.  to  saturated  steam  at  162  Ibs.),  and  divide  by  the 
latent  heat  of  steam  (970-8).     That  is 

-  —  —   -  =7'5i  Ibs.  of  water  from  and  at  212°  F. 

This  figure  can  be  checked  by  the  "  factors  of  evaporation  " 
figure  from  any  engineering  pocket  book. 


120  BOILER  PLANT  TESTING 

To  get  the  "  evaporation  from  and  at  212°  F.  per  1,000,000 
B.Th.U.,"  if  7-52  Ibs.  from  and  at  212°  F.  are  evaporated  per 
Ib.  of  coal,  the  heating  value  of  which  is  11,715  B.Th.U.,  then 
11,715  B.Th.U.  is  equivalent  to  7-52  Ibs.  and  1,000,000  is 

equivalent  to  7'52   x   1,000,000^ 
11715 

(6)  Saving   in    Coal   Bill   Due    to    Economizers. — In    the 
gross  efficiency  figures,   the  boiler  and   ecortomiser  is   62-33 
per  cent,  and  the  economiser  only  is  IO'O2  per  cent,  so  that 
expressed  as  a    percentage    the   saving  in    the    coal    bill    is 

IO'O2    x    TOO 

— — =  1 6- 1   per  cent,  which  can    also    be   checked 

by  empirical  tables  found  in   most  pocket  books,  or  econo- 
miser makers'  catalogues. 

(7)  Saving   in   Coal   Bill  Due    to    Superheaters. — In    the 
same  way   the   gross    efficiency  of   boilers,  economisers    and 
superheaters  is  6570  per  cent,  and  the  superheater  only  3-37 
per  cent,  so  that  the  saving  in  the  coal  bill  due  to  the  super- 

heater  is3'37  X   IOQ  =  5-1  per  cent 
6570 

These  figures  are  the  essential  ones  for  the  true  performance 
of  any  boiler  plant  That  is  to  say,  for  every  ico  Ibs.  of  coal 
put  into  the  plant,  57*20  Ibs.  are  being  used  to  produce  useful 
steam,  the  other  42-8  Ibs.  being  wasted,  8-5  Ibs.  due  to 
auxiliary  steam  and  34-3  parts  to  various  losses  not  yet 
analysed. 

One  of  the  losses  is  radiation  from  the  whole  body  of  the 
plant.  In  my  opinion,  it  is  not  essential  to  determine  this 
experimentally,  and  I  would  not  propose  to  include  it  as  part 
of  the  International  Code.  It  can,  however,  be  determined  if 
required  by  running  a  test  on  the  plant  for  a  number  of  hours, 
the  longer  the  better,  with  the  main  steam  pipes  to  the  factory 
shut  down  and  supplying  just  enough  coal  to  the  plant  to  main- 
tain the  full  boiler  pressure  without  blowing  off.  The  amount 
of  coal  burnt  in  comparison  with  that  of  the  full  working  trial 
will  give  the  radiation  loss,  which  may  correspond  to  anything 


CRITICISMS  OF  EXISTING  CODES  121 

from  5*0  to  lO'O  Ibs.  for  every  100  Ibs.  of  coal  taken  by  the 
plant  The  "  Civils "  Code  (p.  53,  also  p.  79)  seems  to 
regard  this  as  an  essential  part  of  the  test,  but  the  method 
proposed  is  not  at  all  clear,  and  as  far  as  can  be  made  out, 
seems  to  apply  to  the  boiler  only,  and  not  to  the  whole  plant. 
Of  course,  the  radiation  loss  should  include  the  boiler,  econo- 
miser,  superheater  and  all  accessories. 

The  other  sources  of  loss  are  faulty  firing,  that  is,  excess 
or  deficiency  of  air  passing  through  the  fires,  cooling  of  the 
plant  due  to  leakage  of  cold  air,  heat  losses  in  the  ashes,  and 
insufficient  heat  absorption  by  the  boiler,  superheater  and 
economiser,  that  is  too  high  an  exit  temperature  in  the 
chimney  base.  The  "Civils"  Code,  and  to  a  lesser  extent 
the  American  "  Mechanicals  "  Code,  get  in  to  a  terrible  tangle  in 
calculating  these  losses,  and,  in  fact,  approach  the  whole  of  the 
calculations  on  the  assumption  that  these  losses,  and  not  the 
amount  of  heat  put  into  the  plant,  are  the  most  important 
part  of  the  calculations.  It  is  stated  in  the  " Civils"  Code 
(p.  5)  that  the  measurement  of  the  losses  are  "  a  valuable 
check  on  the  accuracy  of  a  trial,"  but  my  point  is  that  in  any 
case  the  loss  figures  are  not  accurate,  even  if  they  were 
necessary. 

For  example,  we  have  in  the  "  Civils  "  Code  (p.  78,  1. 
23,  pp.  80-85,  11.  39-40,  p.  86,  11.  51,  52,  54,  55,  56,  also 
pp.  88-90)  the  particulars  dealing  with  the  amount  of  heat 
passing  away  from  the  plant,  and  the  heat  carried  away  by  the 
excess  air,  in  half  a  dozen  pages  of  complicated  calculations. 
The  basis  is  the  full  analysis  of  the  flue  gas  (CO2,  CO,  O 
and  difference)  to  represent  all  the  gases  leaving  the  plant 
during  the  test,  and  then  the  calculation  of  this  volumetric  gas 
analysis  to  parts  by  weight.  It  is  then  assumed  that  all  the 
carbon  in  the  coal  appears  in  the  flue  gas  as  CO2  and  CO, 
and  following  on  a  complete  analysis  of  the  coal  for  the  per- 
centage of  carbon,  hydrogen,  etc.,  it  is  calculated  how 
many  Ibs.  of  dry  flue  gases  leave  the  boiler  flues  per  Ib.  of 
fuel  burnt.  This  calculation  is  based  on  dry  flue  gases,  b.ut 


122  BOILER  PLANT  TESTING 

they  are  not  dry  as  they  contain,  as  already  seen,  an  enormous 
amount  of  water,  equal  to  8*95  times  the  weight  of  the 
hydrogen  originally  present  in  the  fuel,  together  with  the 
natural  moisture,  but  making  allowance  for  this  we  arrive  at 
the  figure  for  the  weight  of  air*  drawn  into  the  flues  per  Ib. 
of  fuel.  By  another  calculation  on  the  percentage  of  carbon, 
hydrogen,  etc.,  in  the  coal  burnt,  the  theoretical  weight  of  flue 
gases  is  calculated,  and  in  this  way  the  excess  air  is  determined. 
In  order  to  try  and  reduce  the  labour  of  these  calculations  an 
empirical  formula  is  recommended  (p.  85),  namely, 
Heat  carried  away  by  dry  gases  _  Constant  x  a  x  (T  -  t) 

per  Ib.  of  fuel  burnt  C 

Where  a  =  percentage  of  carbon  by  weight  in  the  fuel  after 

correction  for  unburnt  material  in  the  ash. 
C  =  percentage  of  CO2. 

With  regard  to  the  constant,  this  is  explained  as  follows  :— 

"The  constant  for  flue  gas  at  about  500°  F.  may  be  taken 
as  O'6a5  and  the  error  will  not  exceed  I  per  cent,  on  the  heat 
balance,  which  is  well  within  the  limits  of  experimental  error." 

With  regard  to  the  question  of  the  loss  in  heat  in  the  hot 
ashes  (p.  86,  11.  42,  42^),  this  is,  in  my  opinion,  a  matter 
of  little  importance.  The  "  Civils ''  Code  has  to  assume  that 
the  temperature  of  the  hot  ashes  as  withdrawn  from  the  fires 
is  2000°  F.  and  the  specific  heat  of  the  ashes  is  0-3,  and  all 
these  assumptions  reduce  the  "  heat  balance  sheet "  to  a  farce. 
In  order,  therefore,  to  make  this  calculation  for  the  heat  pass- 
ing up  the  chimney,  we  have  to  make  a  complete  and  laborious 
chemical  analysis  of  the  fuel,  in  addition  to  the  heating  value 
by  the  bomb  calorimeter,  an  analysis  of  the  ash,  an  analysis 
of  the  flue  gases,  and  a  whole  series  of  complicated  calculations, 
and  the  results  when  obtained  are  based  largely  on  assump- 
tions. I  would  suggest  that  in  the  International  Code  all  this 
be  cut  out  as  not  essential. 

The  information  obtained  by  the  CO2  Recorder  will  give 
us  without  any  trouble,  by  the  curve,  Fig.  8,  a  figure  for  the 


CRITICISMS  OF  EXISTING  CODES  123 

loss  in  heat  due  to  faulty  firing,  which  is  practically  that 
obtained  at  so  much  expense  and  trouble  by  the  method  of 
the  "Civils"  Code. 

Thus,  for  example,  in  the  specimen  trial  the  figure  for 
CO2  is  6'O  per  cent.,  and  by  the  curve  this  corresponds  to 
1 6  per  cent,  loss  in  coal,  taking  14  per  cent,  as  the  maximum 
CO2  obtainable  in  practice. 

Another  extraordinary  feature  of  the  "Civils"  Code  is 
that  the  whole  of  these  laborious  calculations  have  to  be  gone 
through  all  over  again  for  the  economiser,  and  yet  a  third  time 
for  the  superheater.  I  am  at  a  loss  to  understand  what  is  the 
reason  for  suggesting  that  the  economiser  and  superheater 
should  be  regarded,  from  the  point  of  view  of  gas  analysis,  as 
separate  from  the  boiler,  and  the  essential  figures  for  the 
economiser  and  superheater  can  be  worked  out  in  a  few 
seconds  by  the  method  suggested  on  page  115.  And  to  fur- 
ther add  to  the  confusion,  the  "  Civils"  Code  then  proceeds 
to  give  (p.  80)  an  entirely  fresh  and  empirical  formula  for 
calculating  out  efficiencies  without  the  aid  of  steam  tables,  in 
spite  of  the  fact  that  anyone  can  buy  steam  tables  for  a  few 
pence,  and  the  method  suggested  is  admittedly  not  accurate. 


124 


' 
PART  III. 

SUGGESTIONS  FOR  NEW  FEATURES\VHICH  MAY 
BE  ADDED  IN  THE  FUTURE  TO  AN  INTER- 
NATIONAL CODE  AS  THE  RESULT  OF 
FURTHER  DISCUSSION  AND  INVESTIGA- 
TION. 

i.  The  Question  of  the  Use  of  a  Special  Factor,  Depend- 
ing on  the  Quality  of  the  Fuel,  to  be  Used  in  Calculating 
the  Net  Working  Efficiency  of  the  Plant. — Up  to  the 

present  time,  in  most  boiler  plant  tests  the  efficiency  has  been 
calculated  simply  from  the  actual  amount  of  heat  present  in 
the  fuel,  and  no  allowance  has  been  made  for  different  qualities 
of  fuel,  and  for  the  different  theoretical  efficiencies  possible. 

For  example,  if  one  plant  is  using  the  finest  washed  nuts 
with,  say,  3  per  cent,  ash  and  14,000  B.Th.U.  per  lb.,  and 
another  plant  is  using  merely  refuse  coal  with,  say,  35  per 
cent,  ash  and  7000  B.Th.U.  per  lb.,  and  no  auxiliary  steam  is 
used  in  each  case,  the  efficiency  is  calculated  in  the  same  way 
in  both  instances,  that  is,  on  the  amount  of  heat  actually 
present  in  the  coal.  Thus,  the  first  plant  may  be  working  at 
72  per  cent,  net  working  efficiency  and  the  other  at  59  per 
cent,  and  according  to  the  methods  of  calculation  generally 
adopted,  the  first  plant  is  regarded  as  doing  very  much  better 
than  the  second.  Stated  in  this  way  the  results  are  completely 
misleading,  because  the  fact  is  ignored  that  with  the  good  coal 
the  price  may  be,  say,  £2  los.  per  ton,  and  the  possible 
efficiency  80  per  cent,  and  with  the  inferior  coal  and  the  same 
amount  of  skill  and  attention,  the  efficiency  can  only  be  65  per 
cent,  but  the  price  is  £1  55.  per  ton. 


SUGGESTIONS  FOR  NEW  FEATURES         125 

The  reason  is,  of  course,  that  with  inferior  coal  the  per- 
centage of  ash  is  so  great  that,  even  with  mechanical  stokers, 
it  is  not  easy  to  prevent  excess  air  passing  through  the  fires, 
it  is  much  more  difficult  to  burn  the  coal  with  the  evolution 
of  radiant  heat,  and  an  excess  of  heat  is  lost  in  the  ash. 

This  is,  however,  very  unfair  to  the  plant  using  inferior 
coal,  both  scientifically,  as  well  as  from  a  practical  and  business 
point  of  view.  For  example,  to  look  at  the  matter  in  another 
way,  take  a  case  of  a  plant  burning  200  tons  a  week  of  the 
inferior  coal  at  255.  per  ton,  with  a  net  working  efficiency  of 
59  per  cent.,  and  with  an  annual  coal  bill  therefore  of  £i  2,500. 
If  expensive  coal  of  14,000  B.Th.U.  at  £2  los.  per  ton  is 
substituted,  it  is  quite  true  that  the  efficiency  is  increased  to 
72  per  cent,  and  the  amount  of  coal  burned  is  only  163  tons 
per  week,  yet  the  net  result  of  this  is  to  increase  the  fuel  bill 
of  the  factory  from  £12,500  to  £20,375  Per  annum.  Accord- 
ing to  the  usual  methods  adopted,  however,  as  in  both  the 
Codes,  the  plant  is  now  doing  better,  in  spite  of  the  fact  that 
the  practical  result  would  be  to  lose  £7875  per  annum  !  This, 
of  course,  is  an  absurdity,  and  I  have  in  the  past  tried  to  get 
over  this  difficulty  to  some  extent  by  always  giving  the  cost 
of  evaporation  of  1000  gallons  of  water,  although  this  has  the 
defect  that  it  is  dependent  on  prices  of  fuel,  which  vary  con- 
siderably in  different  neighbourhoods.  I  would  suggest,  how- 
ever, that  this  item  be  included  in  the  International  Code. 
Some  makers  of  appliances  for  steam  generation  understand 
the  point  very  well,  and  many  of  the  remarkable  results  that 
are  published  as  having  been  obtained  with  various  appliances 
will  be  found,  on  investigation,  to  be  really  due  to  the  fact  that 
especially  good  quality  coal  has  been  used.  If  such  coal  had 
been  used  on  the  original  plant,  the  same  results  might  have 
been  obtained  without  the  appliance  at  all. 

Thus,  it  is  a  favourite  method  to  take,  for  example,  a  hand- 
fired  plant  with  natural  draught,  and  simple  fire-bars  burning 
average  coal  of  moderate  price  and  quality,  arid  to  fit  on  some 
appliance  to  burn  cheaper  fuel  with  the  object  of  showing  a 


126  BOILER  PLANT  TESTING 

saving.  The  only  fair  and  reasonable  method  of  proceeding  is 
to  burn  the  same  quality  of  coal  as  before,  and  if  further  trials 
are  carried  out  with  cheap  refuse  coal  or  expensive  good  quality 
coal,  then  to  have  at  the  same  time  analogous  trials  with  these 
coals  on  the  plant  as  originally"  working.  It  is  amazing  the 
number  of  tests  published  that  trust  to  the  steam  user  to  ignore 
these  elementary  facts.  A  given  furnace  stated,  for  example, 
to  save,  say,  30  per  cent,  of  the  coal  bill,  will  be  found  on  inves- 
tigation to  have  been  tested  with  cheap  refuse  coal,  of  which 
only  a  limited  supply  is  available,  as  against  average  priced 
coal  on  the  original  plant.  If,  in  the  later  case,  the  same  re- 
fuse coal  had  been  used,  whilst  the  results  might  not  perhaps 
have  been  as  good  as  with  the  special  furnace,  the  real  saving 
would  have  been  about  10  per  cent,  instead  of  30  per  cent. 
When  this  is  pointed  out  the  reply  is  usually,  as  I  know  from 
experience,  that  the  test  has  been  carried  out  according  to 
the  usual  practice,  and  sufficient  allowance  has  already  been 
made  in  calculating  the  efficiency  from  the  actual  heat  value. 
On  pressing  the  point,  however,  refuge  is  then  as  a  rule  taken 
in  the  "Civils"  Code,  in  which  no  allowance  has  been  made 
for  different  qualities  of  fuel,  although  in  the  test  in  dispute 
no  attempt  has  been  made  to  carry  it  out  according  to  this 
Code. 

What  is  required  is  that  there  should  be  added  to  the 
ordinary  calculated  efficiency  a  further  quantity  X,  which 
would  vary  according  to  the  heating  value  and  quality  of  the 
fuel.  The  value  of  X  would  be  expressed  as  a  curve,  which 
I  would  suggest  calling  the  Standard  Curve  cf  Efficiency  Cor- 
rection for  the  Diminishing  Heat  Value  of  the  Fuel,  so  that  the 
value  of  X  would  increase  as  the  value  of  the  fuel  decreased. 
This  would  put  all  boiler  plants  on  a  real  comparative  basis, 
and  give  proper  credit  to  the  man  who  is  burning  a  cheaper 
and  inferior  fuel,  and  doing  a  national  service  as  well.  Such 
a  curve  could  only  be  obtained  experimentally,  and  this  I 
suggest  would  be  one  of  the  points  of  investigation  for  the 
International  Committees. 


SUGGESTIONS  FOR  NEW  FEATURES         127 

What  would  be  necessary  would  be  for,  say,  twenty  or  so 
thoroughly  representative  coals  to  be  taken,  from  the  highest 
to  the  lowest  quality,  and  a  complete  series  of  experiments 
carried  out  under  various  conditions  of  steam  generation  on, 
say,  "  Lancashire,"  "  Marine,"  and  "  Water-tube  "  boilers  with, 
for  example,  (i)  rated  evaporation,  (2)  20  per  cent,  overload, 
(3)  20  per  cent,  and  (4)  50  per  cent,  below  rated  load,  both 
with  hand  firing,  and  different  types  of  mechanical  stoker. 
If  a  whole  series  of  trials  were  carried  out  in  this  way,  on  a 
well  equipped  experimental  plant,  sufficient  data  would  be 
obtained  to  elaborate  such  a  curve  with  a  considerable  amount 
of  accuracy. 

Based  on  the  experience  of  over  a  thousand  tests,  I  would 
suggest  the  curve  as  given  in  Fig.  21  (next  page).  I  do  not 
pretend  that  this  curve  is  accurate,  because,  as  already  stated,  it 
would  need  to  be  based  on  much  experimental  work,  but  it  is  of 
interest  as  illustrating  the  principle.  Thus,  in  the  Specimen 
Test,  the  value  of  X  with  coal  of  1 1 ,7 1 5  B.Th.U.  would  be  5  -o, 
and  this  would  then  be  added  to  the  figure  of  59-4  per  cent, 
for  the  net  working  efficiency.  The  result,  64-4  per  cent, 
which  would  be  called  the  C.D.H.V.  net  working  efficiency 
(corrected  for  diminishing  heat  value).  In  the  example  just 
mentioned  the  plant  with  14,000  B.Th.U.  coal,  and  72  per 
cent  efficiency,  would  have  added  the  figure  of  0*5,  making 
72-5  per  cent,  efficiency;  and  the  plant  with*  7000  B.Th.U. 
and  59  per  cent,  efficiency  would  have  the  figure  of  23-5, 
making  82-5  per  cent.  The  latter  plant  would,  therefore,  be 
much  the  best  by  calculation,  as  it  is  in  practice. 

2.  Labour,  Attendance,  Repairs,  Upkeep,  Interest  and 
Depreciation. — Another  difficulty  is  that  of  the  cost  of  work- 
ing the  plant,  quite  apart  from  the  fuel  bill.  If,  for  example, 
a  plant  of  ten  "  Lancashire  "  boilers  has  only  four  men  per 
shift  looking  after  it,  together  with  reduced  labour  at  night, 
and  a  wage  bill  of,  say,  £20  per  week,  working  on  60  per 
cent,  efficiency,  and  the  plant  is  then  reorganised  to  work  on 
an  efficiency  of  75  per  cent,  but  the  wage  bill  is  increased  to 


128 


BOILER  PLANT  TESTING 


,£30  per  week,  this  extra  £500  per  annum  ought  to  be  de- 
ducted   in    calculating  the  net    result.      In  the  same  way,  if 


/9ooo 

/eooo 

(fcooo 

<5ooo 

\ 

13000 
I2ooo 
II  000 

\ 

\ 

\ 

\ 

\ 

s 

s 

\ 

*\ 

\ 

Sooo 
8000 

X, 

s 

s 

\ 

sx^ 

x 

X, 

X 

' 

X 

X, 

6<MX 

v 

""V 

^ 

-X 

•^. 

-^ 

5o.o 

"^ 

N-x» 

5 

*  —  , 

-^, 

•*• 

~* 

3oco 
2ooo 

loco 

3   #  J 

6  7    I 

FIG.  21. — Suggested  standard  curve  of  efficiency  correction  for  the  diminishing 
heat  value  of  the  fuel  (coal  only). 

many  additional  appliances  and  instruments  are  installed,  so 
that  the  cost  of  repairs  and   upkeep  is  increased  from,  say, 


SUGGESTIONS  FOR  NEW  FEATURES         129 

£200  to  £500  per  annum,  then  this  extra  £500  should  also 
be  deducted. 

In  almost  all  boiler  plant  tests  these  considerations  are 
ignored,  and  no  instructions  are  given  on  the  point  in  any 
code.  This  is  particularly  unfair  in  the  reverse  instance  on 
a  very  large  plant  of,  say,  sixteen  boilers,  where  mechanical 
stoking  and  mechanical  coal  and  ash  handling  is  installed. 
Twelve  men  per  shift  may  have  been  working  under  hand 
conditions,  and  the  installation  of  mechanical  appliances 
throughout  may  save  the  labour  of  eight  men,  that  is,  several 
thousand  pounds  per  annum  in  wages.  It  is  unfair  that  this 
saving  should  not  be  added  to  the  efficiency  figures,  since  the 
steam  or  power  used  has  been  deducted. 

There  is  also  the  question  of  interest  on  capital,  and  de- 
preciation. A  firm  may  have  a  boiler  plant  of  ten  "  Lanca- 
shire "  boilers  which  has  cost  complete,  say,  £25,000.  If  this 
plant  is  reorganised  to  improve  th£  efficiency  and  a  further 
^  1 5,000  spent  on  economisers,  water- softening  plant,  mechani- 
cal draught,  mechanical  stokers,  instruments  such  as  CO2 
Recorders,  water  meters,  etc.,  then  there  must  be  deducted 
from  the  saving,  interest  on  this  £15,000  and  depreciation  on 
the  new  plant.  If  we  take  the  interest  as  6  per  cent,  and 
depreciation  as  10  per  cent,  this  corresponds  to  an  annual 
sum  of  £2400,  or,  say,  1200  tons  of  coal  to  be  deducted  in 
calculating  the  real  net  saving,  which  makes  a  very  substan- 
tial difference  in  the  figures.  This  important  practical  point 
is  also  ignored  in  all  boiler  plant  tests,  and  some  of  the  pub- 
lished results  of  tests  would  look  very  different  if  such  figures 
were  included.  I  think  that  the  whole  question  should  also 
be  investigated  by  the  International  Committees,  but  would 
suggest  the  following  basis  : — 

In  every  case  the  cost  of  the  labour,  attendance,  repairs, 
upkeep,  interest  and  depreciation  be  calculated,  and  then  ex- 
pressed as  equivalent  tons  of  coal  per  annum.  For  example, 
if  in  a  boiler  plant  of  ten  "  Lancashire "  boilers,  burning 
10,000  tons  of  coal  valued  at  £20,000,  the  total  cost  was 

9 


130  BOILER  PLANT  TESTING 


,000,  the  interest  at  6  per  cent,  and  the  depreciation  at 
10  per  cent,  would  correspond  to  £5600  per  annum,  and  the 
cost  of  labour,  attendance  and  repairs  was  ^2000,  the  total 
cost  would  be  ^7600,  that  is,  3800  tons  of  coal  per  annum  or 
38  per  cent,  of  the  coal  bill.  A  would  suggest  that  the  final 
efficiency  figure  would  then  be  the  C.D.H.V.  net  working 
efficiency,  less  38  per  cent,  of  this  figure,  that  is,  if  the 
C.D.H.V.  was  85  per  cent,  the  final  figure  would  be 

85  -  2975  —  —  -  —  —  =  55'25  percent.     Some  such  method 
100 

as  this  would  get  over  many  practical  difficulties,  and  bring 
into  true  perspective  the  real  practical  value  of  plant, 
machinery  and  appliances  constituting  a  boiler  plant,  including 
all  the  important  items  of  capital  outlay,  repairs  and  labour 
and  attendance.  It  would  do  away  also  with  the  absurdity 
of  a  large  boiler  plant  being  worked  at  a  very  low  evapora- 
tion so  as  to  get  a  high  efficiency.  If,  however,  the  interest 
and  depreciation  on  the  capital  outlay  of  this  large  plant  was 
included,  the  proper  value  of  such  a  proceeding  would  then 
be  apparent  at  once. 

3.  Dust  and  Grit  in  Chimney  Gases.  —  In  connection 
with  the  difficult  question  of  recording  the  amount  of  black 
smoke,  nothing  is  ever  mentioned  about  dust  and  grit  in  the 
chimney  gases,  and  this  point  is  now  becoming  important 
since  the  modern  power  station  practice  is  to  have  very  short 
steel  chimneys.  Although  there  may  be  no  smoke,  the 
amount  of  such  grit  and  dust  given  off  can  be  easily  a  serious 
matter,  as  it  is  thrown  out  over  a  very  restricted  area.  I  am 
of  the  opinion  that  the  International  Committees  should  de-vise 
some  standard  method  of  testing  chimney  gases  for  dust  and 
grit,  so  that  this  would  be  included  in  the  International  Code. 
One  idea  that  suggests  itself  is  to  insert  a  bent  pipe  with  an 
expanding  vertical  nozzle  in  the  chimney  base,  so  that  the 
area  of  the  nozzle  could  be  made  a  standard  proportion  of  the 
inside  area  of  the  chimney  at  this  point  (say  5  per  cent.).  The 
other  end  of  the  pipe  would  be  connected  to  a  metal  box  kept 


SUGGESTIONS  FOR  NEW  FEATURES         131 

by  means  of  a  small  fan  (hand  or  motor  driven)  at  a  standard 
suction  (say  10  per  cent)  above  that  of  the  chimney  base. 
Consequently  5  per  cent,  of  the  chimney  gases  would  be 
pulled  through  the  box,  which  could  be  provided  with  baffles 
and  a  cloth  bag  to  collect  the  solid  material,  which  would  then 
be  weighed  and  expressed  as  so  many  ounces  per  hour,  or  by 
some  other  convenient  term. 

4.  Steam  Meters. — 'Another  point  for  investigation  by 
the  International  Committees  is  the  question  of  using  steam 
meters  to  measure  the  output  of  the  plant  instead  of,  or  in 
addition  to,  the  measurement  of  the  water  evaporated.  The 
"  Civils  "  Code  does  not  mention  steam  meters  at  all,  whilst, 
as  already  seen,  the  American  Code  permits  their  use  for  test- 
ing auxiliaries.  There  is  no  doubt  that  the  logical  method  of 
determining  the  output  of  a  boiler  plant  is  to  measure  the 
useful  steam  actually  passing  into  the  factory,  if  only  this  could 
be  done  with  sufficient  accuracy.  Steam  meters  have  already 
been  referred  to  on  page  103  in  connection  with  the  measure- 
ment of  auxiliary  steam,  and  since  this — in  averages — is,  say, 
6  to  10  per  cent,  of  the  production,  a  steam  meter  is  very 
satisfactory  for  the  purpose.  The  matter  is  not,  however, 
quite  so  easy  when  the  total  output  and  the  net  working 
efficiency  of  the  boiler  plant  have  to  be  calculated. 

There  is  no  doubt  that  the  invention  of  a  simple  and 
reliable  form  of  steam  meter  has  been  one  of  the  most  difficult 
problems  in  engineering.  The  steam  may  contain  different 
amounts  of  water,  and,  if  superheated,  the  temperature  may 
vary  considerably,  whilst  the  amount  of  steam  passing  may 
fluctuate  suddenly  through  a  wide  range,  and  there  may  also 
be  a  pulsating  action.  Further,  as  already  stated,  the  steam 
often  has  a  violent  swirling  motion  in  the  pipe,  so  that  it  is 
very  difficult  to  get  a  true  figure  for  the  average  velocity. 
However,  these  difficulties  have  now  in  general  been  sur- 
mounted, and  there  is  at  present  on  the  market  seven  different 
makes  of  steam  meters. 

Steam  meters  can  be  divided  into    two   general  classes. 


132  BOILER  PLANT  TESTING 

The  first  consists  of  meters  in  which  the  whole  of  the  steam 
passes  through  the  body  of  the  meter,  as  represented  by  the 
"  Bayer  "  and  "  St.  John  "  meters.  In  these  meters  a  cone  or 
disc  is  lifted  off  its  seat  according  to  the  amount  of  steam 
passing,  and  a  recording  mechanism  is  actuated  by  this  means. 

The  second  class  consists  of  meters  in  which  a  disc  or 
plug  is  inserted  in  the  steam  pipe  line,  and  connected  to  the 
recording  mechanism.  In  the  "  British  Thomson-Houston," 
"  Curnon  "  and  "  Sarco  "  meters  the  disc  or  plug  is  a  "  Pitot  " 
tube,  whereas  in  the  "Bailey"  and  "Kent"  meters  the 
principle  is  that  of  a  "Venturi"  tube.  The  amount  of  steam 
passing  is  proportional  to  a  small  difference  of  pressure  shown 
either  by  these  "  Pitot '  or  "  Venturi  "  tube  devices,  and  this 
pressure  varies  from  zero  to  say  f  Ib.  per  sq.  in.  In  measur- 
ing this  small  pressure  and  expressing  it  as  Ibs.  of  steam 
passing  in  the  pipe  the  "  Bailey  "  meter  uses  a  sealed  cell 
floating  in  mercury,  the  "  Curnon "  and  "  Kent "  meters  a 
diaphragm,  and  the  "  British  Thomson-Houston  "  and  "  Sarco  " 
meters  a  modified  "  U  "  tube  with  float. 

The  makers  of  most  of  these  meters  claim  an  accuracy  of 
I  to  2  per  cent,  but  the  trouble  seems  to  be  that  most  meters 
are  not  as  accurate  when  the  passage  of  the  steam  is  fluctuat- 
ing. I  think  that,  subject  to  further  investigations,  steam 
meters  ought  to  be  included  in  the  International  Code  as  a 
useful  addition  to  the  measurement  of  the  steam  output  of  the 
boiler  plant. 


133 


PART  IV. 

DESIGN  OF  REPORT  SHEETS  FOR  THE  NEW 

CODE. 

THE  following  is  the  design  of  (f  Report  Sheets  "  I  would 
suggest  for  use  with  boiler  tests  carried  out  according  to  an 
International  Code.  The  explanation  of  each  item,  the  exact 
method  of  carrying  out  the  test  and  logging  the  results,  say, 
every  half-hour,  and  the  working  log  sheets  for  actual  use  on 
the  test  itself  will  hardly  need  much  description  and  it  will  not 
be  necessary  to  include  it  in  this  book. 

In  general,  however,  the  International  Test  Code  Sheets 
I  would  suggest  be  divided  into  four  main  and  distinctive 
groups  in  logical  order,  namely,  (i)  A  General  Description  of 
the  Whole  Plant,  (2)  Particulars  Relating  to  the  Burning  of 
Fuel,  (3)  Particulars  relating  to  the  Production  of  Steam, 
(4)  Tabulated  Results. 

After  the  preliminary  sheet,  item  (i),  is  a  detailed  descrip- 
tion of  every  part  of  the  plant  in  the  natural  sequence,  com- 
mencing with  the  boilers,  following  through  with  everything 
relating  to  coal,  that  is,  coal  and  ash  handling  plant,  grates, 
control  of  firing,  economisers,  chimney  flues  and  mechanical 
draught,  then  following  with  details  relating  to  steam  pro- 
duction, such  as  boiler  feed-water,  method  of  boiler  feeding, 
measurement  of  feed-water,  superheaters,  measurement  of 
steam  output  and  steam  pressure.  This  will  give  a  complete 
account  of  the  details  of  the  equipment  of  the  plant,  and,  in 
my  opinion,  it  is  much  better  to  be  embodied  in  the  Test 
Sheets  in  this  way. 

Item  (2)  deals  with  all  the  particulars  of  the  test  relating 
to  the  fuel,  namely,  the  description  and  quality  of  the  fuel,  the 


134  BOILER  PLANT  TESTING 

analysis,  the  amount  used,  the  particulars  as  regards  the  ash, 
flue  gas  temperatures,  draught,  flue  gas  analysis,  and  black 
smoke. 

Item  (3)  deals  in  the  same  way  in  order  with  each  item 
relating  to  the  production  of  steam,  namely,  the  amount  of 
water  evaporated,  the  temperature  of  the  water,  the  steam 
pressure,  the  amount  of  superheat,  and  the  auxiliary  steam  or 
power  used  for  the  production  of  steam. 

Item  (4)  then  gives  the  tabulated  results,  that  is,  the 
water  evaporated  per  Ib.  of  coal,  "  from  and  at,"  "  from  and 
at"  per  1,000,000  B.Th.U.,  and  the  efficiency  figures,  that 
is,  the  net  working  efficiency  of  the  plant,  and  the  separate 
figures  for  the  boiler,  economiser  and  superheater.  Also 
the  cost  for  evaporation  of  1000  gallons  of  water. 

The  last  sheet  is  the  "Long  Check  Test,"  giving  the 
essential  figures  of  the  water  evaporated,  and  the  amount  and 
analysis  of  the  coal  used. 

The  example  given  of  a  Report  on  these  lines,  with  the 
figures  of  an  actual  test,  will  doubtless  make  the  matter  clear. 

COMPLETE  STEAM  BOILER  PLANT  TEST 

REPORT. 

(Test  Carried  out  According  to  the  International  Steam  Boiler 
Plant  Test  Code.} 

GENERAL  PARTICULARS. 

(a)  Boiler  plant  situated  at          -.         .  Manchester. 

(b)  Name  of  plant       .    •-'  .  -       .         .  Main  boiler  plant  (paper  mill). 

(c)  Date  of  test  ....  June  21-28,  1921. 

(d)  Duration  of  test  ....  8-00  hours. 

(e)  Duration  of  long  check  test  .         .  1 68 'oo  hours. 

(/)  Test  carried  out  by       .         .         .  — 

(£•)  Test  carried  out  in  the  presence  of  —  —  — 

(h}  Object  of  the  test  .  .  .To  find  the  performance  figures 

for  the  present  ordinary  running 
from  week  to  week. 

(z)  General  remarks  ....  The  present  summer  load  is 

roughly  10  per  cent,  less  than 
the  winter  load. 


DESIGN  OF  REPORT  SHEETS 


135 


GENERAL  DESCRIPTION  OF  THE  BOILER  PLANT. 


i.  BOILERS. 
(a)  Type  of  boiler  .         . 
(0)  Number  of  boilers  on  the  plant 

(c)  Number  of  boilers  used  on  the 

test         ... 

(d)  Chief  dimensions 

(e)  Heating  surface  per  boiler 
(/)  Maker     .         ... 
(g)  Date  installed  .         .       -., 

(h]  Maker's  rating  of  boiler  output 
(i}  Amount  of  water  equivalent  to  i 
in.   of   gauge-glass    at    com- 
mencing level  of  test 
(/)  Brief  resume  of  last  report  of 

insurance  company 
(k)  Condition  of  the  brickwork 
(/)  Condition  of  the  covering  . 

(m)  Remarks          .... 


"  Lancashire  ". 
3- 

2. 

30  x  8  ft. 

1000  sq.  ft. 

X. 

One  boiler  1910,  two  boilers  1914. 

7500  Ibs.  steam  per  hour. 


950  Ibs.  per  boiler. 

General  condition  of  boiler  very 
good  but  fair  amount  of  scale. 

Very  bad. 

Very  bad.  Lagging  is  of  an  in- 
ferior quality  and  very  old. 

The  brickwork  is  generally  in  a 
deplorable  condition,  and  the 
cold-air  leakage  is  enormous. 


2.  MECHANICAL  COAL  AND  ASH  HANDLING. 

(a)  Is   the  coal  handled  mechanic- 


ally?     .     •    .         .         . 
(b}  If  so,  state  the  following  parti- 
culars : — 

(01)  Type  of  plant       .         .         . 

(02)  Name  of  maker  .         .         * 

(03)  Maker's  reference  number   . 

(04)  When  installed    .         . 

(05)  Number   of  hours   working 

compared  with  the   boiler 
plant        .         .         . 

(06)  Power  required  to  work  the 

plant        .      ...;•'«         . 

(07)  Remarks     . 

(c)  Is  the  ash  handled  mechanically 

(d)  If  so,  state  the  following  par- 

ticulars : — 


Yes. 


"  Boot  "  elevators  to  each  stoker. 

X. 

42,619. 

1915. 

Continuously     day     and     night. 
Stopped  at  week-ends. 


2-85  H.P. 

Have  not  had  much  trouble 

working. 
No. 


in 


136 


BOILER  PLANT  TESTING 


(d\)  Type  of  plant 
(d2]  Name  of  maker  .         .  •*     . 
(</3)  Maker's  reference  number  . 
(</4)  When  installed    . 
(</5)  Number   of  hours   working 
compared  with  the  boiler 
plant         .         .         . 
Power  required  to  work  the 
plant         .         .         .   |     . 
Remarks     .... 


(d6) 


3.  GRATES. 

(A)  Is  the  firing  hand  or  mechanical 

(B)  If  hand-fired,  state  :—      .         . 
(B i )  General  type  of  fire-bar 

(62)  If  special   make,  name  of 

maker    .... 

(63)  If  mechanically  moved,  state 

power  required 

(64)  Remarks    .         .         .         . 

(C)  If  mechanically  fired,  state  : — 
(Ci)  Type  of  stoker  (sprinkling, 

coking  overfeed,  or  cok- 
ing underfeed) 

(C2)  Name  of  maker 

(C3)  Maker's  reference  number  . 

(€4)  When  installed  .         .      ,. 

(C5)  Amount  of  power  required 
to  drive  the  stoker 
mechanism  per  boiler 

(C6)  Remarks     . 


(D)  Total  grate  area  on  test 

(E)  Length  of  bars  (inc'uding  dead 

plate) 

(F)  Total  width  of  furnace 


1-25  H.P. 

A  spiral  screw  type  of  ash  ele- 
vator was  originally  installed, 
but  scrapped  after  two  years 
because  of  breakdowns.  Ashes 
now  taken  away  by  hand  in 
wheelbarrows. 

Mechanical. 
Not  hand-fired. 


Coking  overfeed. 
X. 

51,206. 

With  the  boilers.    One  in  1910, 
two  in  1914. 


1-25  H.P. 

The  drive  is  a  small  non-condens- 
ing steam  engine,  and  the  ex- 
haust is  blown  to  atmosphere. 

69-00  sq.  ft. 

5  ft.  9  ins 
3ft. 


DESIGN  OF  REPORT  SHEETS 


137 


(G)  Average  air  space  between  the 

bars     . 
(H)  If  steam  jets  are  used,  state  :  — 

(Hi)  Number  of  nozzles  per 
boiler  under  front  of  fires 

(H2)  Number  of  nozzles  per 
boiler  under  back  of  fires 

(H3)  Number  of  nozzles  per  boiler 
over  the  top  of  the  fires  . 

(H4)  Approximate  diameter  of 
the  nozzles  .  .  . 

(H5)  Size  of  steam  pipe  supply- 
ing the  nozzles 

(H6)  How  is  the  valve  on  this 
steam  pipe  supplying  the 
nozzles  generally  worked  ? 

(H7)  Is    there    any    method    in 
use   of  determining    the 
amount    of    steam   used 
by  these  nozzles 
.    (H8)  Remarks    . 


(I)  Is  the  boiler  fitted  with  any 
smoke  preventer  or  other 
special  type  of  apparatus 
auxiliary  to  the  grates  ? 

(J)  How  are  the  boiler  dampers 
generally  worked  ? 

(K)  Can  they  be  controlled  from  the 
firehole  ?  .  '...'.. 

(L)  General  remarks 


4.  CONTROL  OF  FIRING. 

(A)  Is    the     firing     controlled    by 

means  of  flue  gas  analysis  ? 

(B)  If  a  CO2  Recorder  is  used,  state  :- 


|  in. 

14. 
None. 

2. 

I  in. 

fin. 

Full  open  all  the  time. 


None. 

No  difference  is  made  to  the 
valve  controlling  the  nozzles 
which  is  left  full  open  all  the 
time  irrespective  of  the  speed 
of  working. 


None. 
Full  open. 

No. 

The  dampers  are  worked  by 
weights  but  the  chains  are 
only  short  and  the  weights 
hang  over  the  back  of  the 
boilers. 


No. 


138 


BOILER  PLANT  TESTING 


(Bi)  Is  more  than  one  recorder 
in  use  ?    . 

(62)  Name  of  maker  .         . 

(63)  Is    it    being    worked    con- 

tinually ?          . 

(84)  Is  it  in  good  condition  anql* 

giving  good  results  ? 

(85)  Remarks    .         .         . 


(C)  Is  an  "  Orsat "  or  other  hand 

apparatus  in  use  ?  If  so,  how 
often?  . 

(D)  Is   there  any  method   of  col- 

lecting flue  gas  analysis  over 
a  number  of  hours?  If  so, 
give  a  description 

(E)  Is  the  plant  fitted  with  draught 

gauges  ?  If  so,  state  par- 
ticulars -  .... 

(F)  General  remarks 

5.  ECONOMISERS. 

Is  the  plant  fitted  with  economisers 

at  work  ?     . 
If  so,  state  : — 

(A)  Name  of  maker    . 

(B)  Maker's  reference  No. 

(C)  When  installed      . 

(D)  Number  of  tubes  in  the  in- 

stallation 

(E)  Of  what  metal  are  the  tubes 

composed 

(F)  Number   of    tubes    at    work 

during  the  test 

(G)  Height  of  tubes  (or  length)   . 
(H)  Total  heating  surface  of  the 

installation 

(I)  Number  of  tubes  wide    . 
(J)  General  arrangement 
(K)  Method      of      driving      the 

scrapers  .         .         . 


No. 
X. 

No,  out  of  order. 

No,  out  of  order. 

The  CO2  Recorder  has  not  worked 
for  several,  months,  the  pen 
mechanism  being  out  of  order. 


None  in  use. 


None. 


One  draught  gauge  in  fan  inlet. 
No  attention  is  paid  to  flue  gas 
analysis  and  draught  regulation. 


Yes. 

X. 

25,625. 
1908.  . 

480. 
Cast  iron. 

480. 
9  ft. 

4800  sq.  ft. 
10. 

Straight  line. 

Small  steam  engine  supplied  with 
economiser. 


DESIGN  OF  REPORT  SHEETS 


139 


(L)  Conditions  as  regards  scale 
from  the  last  report  of  the 
insurance  company  . 

(M)  Conditions  as  regards  cor- 
rosion . 

(N)  Is  a  circulator  fitted  ?  If  so, 
state  particulars  . , 

(O)  Is  cold  water  (100°  or  under- 
run  through  the  economiser 
at  night  or  at  week-end  ?  . 

(P)  Condition   of  the    brickwork 

(Q)  Remarks. 


6.  CHIMNEY. 

(A)  Height  above  firing  level  . 

(B)  Height  above  ground 

(C)  Internal  dimensions  (top) 

(D)  Internal  dimensions  (bottom)     . 

(E)  Material,  brick,  stone  or  steel  . 

(F)  Shape,    circular,   square,   hori- 

zontal ..... 

(G)  When  was  it  erected  ? 
(H)  General  condition    . 

(I)   Is  it  lined  with  fire-brick  inside  ? 

If  so,  for  what  height  ? 
(J)  Will  it  stand  cutting  for  another 

entrance  ?    .         . 
(K)  Are     the     foundations      good 

enough  for  the  height  to  be 

increased  ?   .         . 
(L)  Remarks          .         .         .         . 


7.  FLUES. 

(A)  Give  a  thumb-nail  sketch  of  the 

general  run  of  the  plant 

(B)  What  is  the  internal  height  of 

the  main  flue  ?     . 

(C)  What  is  the  internal  width  of 

the  main  flue  ? 


Fairly  good. 

Slight  signs  of  wasting  at  the 
bottom. 

None  fitted. 

Yes.  Cold  water  (60°)  seems  to 
be  run  in  at  week-ends. 

Fairly  good. 

The  whole  economiser  seems  to 
be  subsiding  a  little  at  the 
chimney  end,  the  ground  being 
bad. 

Not  known  exactly,  about  1 50  ft. 

About  3  ft.  more. 

6ft. 

7  ft.  9  ins.  diameter. 

Brick. 

Circular, -square  base  12  ft.  high. 
About  1900. 
Very  good. 

Yes.    About  one-third  the  height. 
Yes. 


Yes. 

Chimney  generally  is  in  fine  con- 
dition and  when  built  originally 
was  meant  for  about  six  boilers. 


5  ft.  6  ins. 
3ft. 


140 


BOILER  PLANT  TESTING 


(D)  Do  these  dimensionsihold  good 

from    the     economiser    exit 
right  into  the  chimney  ? 

(E)  Are  the  flues  damp  ? 

(F)  If  "  Lancashire  "  or  "  Cornish  " 

boilers  what  is  the  dimens** 
ions  of  the  smallest  space  in 
the  side  flues  ? 

(G)  Remarks 


8.  MECHANICAL  DRAUGHT. 

If  mechanical  draught  is  in  use,  is 
it  induced,  forced,  or  "  balanced  "  ? 
State  :— 

(A)  Name  of  maker  of  fan  . 

(B)  Type    of    fan    (multiple    or 

paddle  bladed) 

(C)  Maker's  reference  number    . 

(D)  When  installed    . 

(E)  Is  fan  full  housing  or  not?    . 

(F)  Area  of  fan  inlet  . 

(G)  Area  of  fan  discharge  . 
(H)  Diameter  of  fan  runner 

(I)   Is  the  fan  provided  with  ring- 
lubricated      and      water- 
cooled  bearings  ? 
(J)  How  is  the  fan  driven  ? . 
(K)  If  fan  driven  by  steam  engine, 

state  :  — 

(Ki)  Length  of  stroke     . 
(K2)  Area  of  piston 
(K3)  Maximum  speed 
(K4)  Is     the     engine     direct- 
coupled  or  is  it  belt- 
driven 

(K$)  If  direct-coupled,  is  the 
fan  and  engine  on  com- 
bined cast-iron  bed- 
plate? 

(K6)  Is  the  full  boiler  pressure 
on  the  fan  engine  or  is 


Yes. 
No. 


10  ins. 

The  brickwork  of  the  flues  is  fairly 

good,    but    rather    leaky,    and 

should  be  "  pointed  ". 


Yes.     Induced  draught. 
X. 

Multiple  blade. 

123. 

1910. 

Full  housing. 

40  ins.  diameter. 

28  sq.  ft.  (effective). 

40  ins. 

Two  bearings  ring-lubricated,  cne 

water-cooled. 
High-speed  engine. 


6  ins. 

9  ins.  diameter. 

615  R.P.M. 


Direct-coupled. 


Yes. 


DESIGN  OF  REPORT  SHEETS 


141 


there  a  reducing  valve 
fitted  ?  If  so,  what  is 
the  steam  pressure  on 
the  engine  stop  valve  ? 
Is  a  surplus  valve 
fitted?  .  . 

(K7)  Can  the  speed  be  con- 
trolled from  the  fire- 
hole?  ..,'.. 

(K8)  What  is  done  with  ex- 
haust steam  from  the 
engine? 

(Kg)  Remarks 

( L)  If  fan  driven  by  electric  motor, 
state  :— 

(Li)  Name  of  maker  of  motor 

(L.2)  Maker's  reference  number 

(L.3)  Rated  maximum  revolu- 
tions per  minute.  Out- 
put of  motor,  amps. 
Output  of  motor,  volts 

(L4)  Is  the  motor  direct- 
coupled  or  driven 
(chain,  belt  or  rope)  ?  . 

(L-5)  If  direct-coupled,  is  the 
fan  and  motor  on  com- 
bined cast-iron  bed- 
plate ? 

(L6)  What  is  the  figure  of 
electric  current  avail- 
able ?  amps.,  volts 

(L7)  Is  the  current  generated 
on  the  works  or  from 
outside  current  ? 

(L8)  What  is  the  real  net  price 
paid  for  the  current  ?  . 

(Lg)  Can  the  speed  be  con- 
trolled from  the  fire- 
hole?  .  .  . 

(Lio)  Remarks 

(M)  If  fan  be  driven  from  a  line 
shaft,  state  : — 


Full  boiler  pressure.     No  surplus 
or  reducing  valve. 


No. 


Blown  away  in  the  air. 
Fan  discharge  not  good. 


142 


BOILER  PLANT  TESTING 


(Mi)  Method   of  drive  (rope, 

chain,  belt) 

(M2)  Speed  of  driving  shaft    . 
(M3)  What  are  the  usual  run- 
ning    hours     of     this 
shaft?       "    .         . 
(M4)  Is  there  a  friction  clutch 
or  other   arrangement 
to  disconnect  the  fan 
at  will  ? 

(N)  If  any  other  method  driving 
the  fan  is  adopted,  give 
full  particulars 

(O)  Normal    speed,    revolutions 

per   minute  at  which  the 

fan  is  run          .•".." 

(P)  Maker's  maximum  rating  of 

the    mechanical    draught 

plant        .... 

(Pi)  Revolutions  per  minute    . 

(P2)  Cubic  feet  of  gas  or  air 

handled  at  stated  tem- 

prrature  (350°  F.)  per 

minute 

(P3)  B.H.P.  taken  at  this  maxi- 
mum rating 

(P4)  Remarks  .  .  . 
(Q)  Is  the  draught  given  sufficient 
(R)  General  remarks  . 


9.  BOILER  FEED-WATER. 

(A)  What  is  the  source  of  the  feed- 

water  ? 

(B)  If  more  than  one  source  is  used, 

state  the  usual  proportions   . 

(C)  Is  the  water  muddy?     If  so,  is 

any  filtering  plant  used  ?  and 
give  description    . 

(D)  Is  there  any  scale  ? 

(E)  Is  there  any  corrosion  ?    . 


No  other  method. 


550  R.P.M. 


615  R.P.M. 


23,000. 

23. 

Not  quite. 

The  fan  as  installed  is  hardly  big 
enough  and  seems  to  be  throttled 
by  a  bad  discharge  to  the 
chimney. 


River. 

No  other  source. 

Not  particularly.      No  filtering 

plant  used. 
Yes. 
A  little. 


DESIGN  OF  REPORT  SHEETS 


143 


(F)  Is  any  chemical  or  boiler  com- 
position used  ?    If  so,  give  : — 
(Fi)  Name  of  composition 
(F2)  Name  of  maker  . 
(F3)  How    it    is    added    to   the 

boiler?  .         . 

(F4)  Does  it  give  satisfactory  re- 
sults ?     .         . 
(F5)  Remarks     .     '-.'.. 


(G)  If  any  type  of  water-softening 

plant  is  in  use,  state  : — 
(Gi)  Name  of  maker 
(G2)  Maker's  reference  number 
(Gs)  When  installed  . 
(G4)  Maker's     rated    output    of 

softened    water,    gallons 

per  hour 
(G5)  How   many   hours    settling 

does  the  plant  allow  of? 
(G6)  At  what  output  is  the  plant 

being  worked  ? 
(G7)  If  lime  is  used,  is  it  as  lime 

cream  or  milk  of  lime  ?  . 
(G8)  How  many  time's  a  day  is 

the  water  analysed  ? 
(Gg)  What  is  average  figure  for 

the  analysis  before  treat- 
ment ?    .         .     •    . 
(Gio)  What    is    average    figure 

for     the     analysis     after 

treatment  ?     . 
(Gil)  Remarks  .         .         '. 

(H)  Is  any  special  method  adopted 
for  the  prevention  of  corro- 
sion? .  .  . 

(I)  Is  a  trace  of  alkali  in  the  steam 
prejudicial  to  the  use  of  the 
steam  ? 


None. 


A  boiler  composition  was  used 
before  the  water-softening 
plant  was  installed. 

Yes. 
X. 

^578 
1910 


2000  gallons. 
2  hours. 
About  1500. 
Lime  cream. 
Once. 

21°  total  hardness. 

8°. 

Softening  plant  is  not  being  par- 
ticularly well  looked  after. 

No. 

No. 


144 


BOILER  PLANT  TESTING 


10.  METHOD  OF  BOILER  FEEDING. 


(A)  If  an  injector  is  used,  state  : — 
(Ai)  Is  it  in  regular  use  or  only 

as  a  stand-by  ? 
(A2)  Is    it   live    steam,    exhaust 

steam,  or  mixed  pressure  ? 
(A3)  Name  of  maker  . 
(A4)  Remarks    .... 

(B)  If  a  boiler  feed  pump  is  used, 

state  :  — 
(Bi)  Type  of  pump      .         .         . 

(62)  Name  of  maker 

(63)  Maker's  reference  number  . 

(64)  When  installed  .         .  •     ... 

(65)  Maker's  rated  duty,  amount 

of  water  pumped  under 
given  conditions  of  power 
or  steam  supply,  speed, 
and  boiler  pressure 

(B6)  Amount  of  suction  lift  to  the 
pump  .  .  .  . 

(67)  Average  speed  of  pump 

(B8)  If  steam  driven,  what  is 
done  with  the  exhaust 
stearn  ?  .  .  T 

(69)  Average  steam  or  power 
taken  by  the  pump 

(Bio)  Remarks  .         .         . 

(C)  If  feed-water  regulators  are  in 

use,  state  : — 
(Ci)  Number    of    regulators    at 

work  .         .'•'.". 
(€2)  Name  of  maker  . 
(€3)  When  installed  . 
(€4)  Remarks     .... 

(D)  General  remarks 


Only  as  a  stand-by. 

Live  steam. 

X. 

Practically  never  used. 


Vertical  direct-acting. 

X. 

26,727 

1910. 


1 500  gallons  at  1 2  double  strokes 
per  minute  with  and  against 
150  Ibs.  gauge. 

None  falls  from  overhead  tank. 
About     15    double    strokes    per 
minute. 


Blows  away  in  the  air. 
Approximately  1 50  Ibs.  steam  per 

hour. 
Feed  pump  gives  no  trouble  at  all. 


3- 
X. 

1914. 

Do  not  work  particularly  well. 


ii. 


MEASUREMENT  OF  BOILER  FEED-WATER. 


(A)  Is  there  any  method  in  use  of 
measuring   continuously  the 


DESIGN  OF  REPORT  SHEETS 


145 


amount  of  feed-water  pumped 
to  the  boilers  ? 

(B)  If  tanks  are  used  give  a  descrip- 

tion    ..... 

(C)  If  a  water  meter  is  used,  state  .  — 
(Ci)  Name  of  maker. 

(C2)  Maker's  reference  number  . 

(Cs)  When  installed  . 

(C4)  Is  it  used  regularly  ?  .         . 

(C5)  Is  there  any  test  tank  or 
other  method  in  use  for 
testing  its  accuracy  ? 

(D)  General  remarks 

12.  SUPERHEATERS. 

If  the  plant  is  fitted  with  superheaters, 
state  :— 

(A)  Number  of  boilers  fitted 

(B)  Number  used  on  test    . 

(C)  Name  of  maker    . 

(D)  Maker's  reference  number    . 

(E)  When  installed      .       •  .         . 

(F)  Can   the  superheat  be   con- 

trolled with  dampers  ? 

(G)  Is  the  superheat  fitted  with 

bye-pass  to  main  steam 
circuit?  .... 

(H)  Number  of  tubes  per  super- 
heater .... 

(I)  Heating  surface  of  tubes  per 
superheater 

(J)  What  is  the  maker's  rated  out- 
put, temperature  rise  per 
stated  evaporation  of  the 
boilers  at  stated  pressure  ? 

(K)  Is  provision  made  for  further 
tubes  to  be  added  if  neces- 
sary to  the  existing  super- 
heater header  ? 

(L)  General  remarks  . 


10 


No. 


Staff  have  no  idea  of  the  amount 
of  water  evaporated. 


3- 

2. 

X. 


With  the  boiler 
1914. 

No. 


No. 


36. 

176  sq.  ft. 


1 00°  F.,  superheat. 


one  1910,  two 


No. 

Superheaters 
trouble. 


have     given     no 


146 


BOILER  PLANT  TESTING 


13.  MEASUREMENT  OF  STEAM  OUTPUT. 


Is  there  any  steam  meter  installed 
to  measure  the  actual  steam  output 
of  the  plant  ? 

If  so,  state  : —  ^ 

(A)  How    many    steam     meters 

installed  ? 

(B)  At  what  points  are  they  in- 

stalled?   . 

(C)  Name  of  maker    . 

(D)  Maker's  reference  number    . 

(E)  General  remarks  . 


14.  STEAM  PRESSURE. 

(A)  What  is  the  blow-off  pressure 

of  the  plant?  If  different 
boilers  have  different  pres- 
sure, give  full  particulars 

(B)  What  is  the  lowest  pressure  per- 

missible on  the  plant  without 
reducing  the  factory  effici- 
ency, that  is,  what  margin  of 
pressure  is  permissible  ? 

(C)  General  remarks 


None. 


They  seem  to  be  impressed  with 
the  idea  of  installing  steam 
meters. 


1 50  Ibs.     Only  one  pressure. 


140  Ibs.      10  Ibs.  margin. 

Some  low-pressure  steam  is  used 
through  a  reducing  valve,  but 
is  not  much,  and  this  mill  seems 
to  do  very  little  "  boiling  ". 


PARTICULARS  RELATING  TO  THE  BURNING 
OF  FUEL. 

15.  DESCRIPTION  AND  QUALITY  OF  FUEL  USED. 


(A)  Nature  of  fuel 

(B)  Name  of  fuel  .... 

(C)  Price  per  ton  delivered  to  the 

firehole  or  fuel  conveyers 

(D)  What  is  the  average  fuel  used 

all  the  year  round  ? 

(E)  Remarks  .... 


Small  slack. 
X. 

£2  55.  per  ton. 

Small  slack  as  above. 
In  general,  have  not  used  much 
other  coal. 


DESIGN  OF  REPORT  SHEETS 


16.  ANALYSIS  OF  THE  FUEL. 

(A)  Gross  B.Th.U.  in  dry  coal  per 

lb.,  as  fired  .... 

(B)  Net  B.Th.U.  per  lb.  corrected 

for  moisture  in  coal 

(C)  Percentage  of  ash     . 

(D)  Percentage  of  water 

(E)  Remarks          .... 

17.  AMOUNT  OF  FUEL  USED. 

(A)  Total  amount  of  fuel  used  on 

test 

(B)  Corresponding   fuel  burnt   per 

boiler  per  hour     . 

(C)  Corresponding  fuel  burned  per 

sq.  ft.  grate  area  per  hour    . 

(D)  Is  there   much    difference   be- 

tween one  hour  and  another 
in  the  fuel  consumption  on 
the  test?  '.  V.  . 

(E)  Is  there  much  difference  in  fuel 

consumption  on  individual 
boilers?  ; 

(F)  Remarks  .... 


1 8.  ASH  PARTICULARS. 


12,608. 

11,715- 
1 1  -o  per  cent. 
6-5  per  cent. 

This  coal  is  stated  to  be  about 
average  quality. 


1  5,960  Ibs. 


997-5 


28-5  Ibs. 


Not  much. 


No. 

Load  is  very  steady  for  a  paper 
mill.  Approximate  variation 
in  steam  demand  per  half-hour 
does  not  exceed  20  per  cent. 


(A)  Total  amount  of  ash  produced 

(Ibs.)    .....  Not  taken. 

(B)  Percentage  of  unburnt  material 

in  ash  (by  analysis)      .         .  —  —  — 

(C)  Corresponding  B.Th.U.  per  lb. 

(D)  Remarks 

19.  FLUE  GAS  TEMPERATURES. 

(A)  Average    temperature    leaving 

boiler  .         .  .         .     700°  F. 

(B)  Average    temperature    leaving 

superheater  .         .         .     580°  F. 


148 


BOILER  PLANT  TESTING 


(C)  Average   temperature    entering 

economiser 

(D)  Average    temperature    leaving 

economiser  .... 

(E)  Average   temperature  at  chim- 

ney base 

(F)  Remarks  .... 

20.  DRAUGHT. 

(A)  Draught   in    chimney   base   or 

near  fan  inlet,  ins.  W.G. 

(B)  Draught  at  exit  (or  side  flues) 

of  boiler,  ins.  W.G. 

(C)  Draught   over  the   boiler  fire, 

ins.  W.G 

(D)  If    forced     draught,     pressure 

over  fire,  ins.  W.G. 

(E)  If  forced  draught,  pressure  in 

ash-pit,  ins.  W.G. 

(F)  Remarks  .... 

21.  FLUE  GAS  ANALYSIS. 

(A)  Complete  analysis. 

(A  i )  Percentage  of  CO2 

(A2)  Percentage  of  oxygen 

(A3)  Percentage  of  CO 

(A4)  Percentage  of  nitrogen  (by 

difference) 
(A 5)  Average      of     how     many 

analyses 
(A6)  Remarks    .... 

(B)  Combustion  recorder  figures     . 
(B  i )  Percentage  of  CO3 

(62)  Average     of     how      many 

analyses 

(63)  How  many  hours  run 

(64)  Remarks    .... 

22.  BLACK  SMOKE. 


570°  F. 
400°  F. 

400°  F. 

No  pyrometers  are  installed  per- 
manently on  the  plant. 


0-95  in. 
0-50  in. 
0-20  in. 
No  forced  draught. 

No  forced  draught. 
As   already   stated,    fan   not   big 
enough,  and  badly  installed. 


5-8  per  cent. 
14-5  percent. 
0*2  per  cent. 

79-5  per  cent. 

Six    different    samples   of   about 
15,000  c.c.  each. 


6-00  per  cent. 

About  150. 
8-00  hours. 

As  already  noted  there  is  a  lot  of 
leakage  of  cold  air. 


Is   the   plant   troubled   with    black 
smoke  No. 


Very  good  on  the  whole. 


DESIGN  OF  REPORT  SHEETS 


149 


PARTICULARS  RELATING  TO  THE    PRODUCTION 
OF  STEAM. 

23.  AMOUNT  OF  WATER  EVAPORATED. 

(A)  Method  of  measuring  the  water 

on  the  test  .         .    .•     » 

(B)  Total    net    amount    of    water 

evaporated  on  the  test  (Ibs.) 

(C)  Corresponding  water  evaporated 

per  boiler  per  hour  (Ibs.) 

(D)  Corresponding    water    evapor- 

ated per  sq.  ft.  grate  area  per 
hour  (Ibs.)   . 

(E)  Remarks          .         .         .         . 


Calibrated  pressure  meter. 
105,328  Ibs. 
6583  Ibs. 


190-8  Ibs. 

.  The  variation  in  demand  per 
half-hour  is  less  than  usual 
for  a  paper  mill  (see  test  log 
figures). 

24.  TEMPERATURE  OF  FEED-WATER. 

(A)  Average     temperature     before 

economisers          .        ^        .     121°  F. 

(B)  Average      temperature      after 

economisers          .  .       .       ...     296°  F. 

(C)  Corresponding    percentage     of 

coal   bill    saved    by   econo- 
misers 

(D)  Remarks 


1 6- 1  per  cent. 

The    economiser   is  doing  ex- 
tremely well. 


25.  STEAM  PRESSURE. 

(A)  Average  Ibs.  per  sq.  in.,  gauge 

(B)  If  different   pressures    on    the 

same  plant,  give  the  separate 
averages  for  each  division  of 
boilers  .... 

(C)  Average  Ibs.  per  sq.  in.,  absolute 

(D)  Remarks          .... 

26.  SUPERHEAT. 

(A)  Temperature  of  saturation  of 
steam  at  the  average  pres- 
sure of  the  plant  . 


147  Ibs. 


Only  one  pressure. 
162  Ibs. 

Steam    pressure  is  maintained 
on  the  whole  very  well. 


364-2°  F. 


ISO  BOILER  PLANT  TESTING 

(B)  Average  temperature  of  super- 

heated steam  leaving  the 
superheaters  on  boilers  fitted 
with  superheaters  .  -475°  F.  All  fitted. 

(C)  Average  temperature  of  super- 

heated   steam    leaving     the* 

plant  (boilers  fitted  and  not 

fitted  with  superheaters  both 

included)      .         .         .         .     475°  F.     All  fitted. 

(D)  Corresponding  average  degrees 

of  superheat          .         *         .     475°  F. 

(E)  In  general   is  each    individual 

superheater  giving  the  same 
amount  of  rise  ?  .  .  .  Yes. 

(F)  Percentage  saving  in  the  coal 

bill  due  to  superheaters          .    5-1  per  cent. 

(G)  Remarks.  Superheater      installation      in 

general  working  very  well. 

27.  AUXILIARY  STEAM  OR  POWER  USED  FOR  THE  PRO- 
DUCTION OF  STEAM. 

(A)  Mechanical  coal  handling         .     0-4  per  cent. 

(B)  Mechanical  ash  handling          \     0-3  per  cent. 

(C)  Mechanical  stoker  or  hand-fired, 

mechanical  moving   furnace 

drive   .         .         .         -'.'•'•  0-5  per  cent. 

(D)  Steam  jets       .        '.."..      .  8-05  per  cent. 

(E)  Mechanical  draught          .         .-  2*4  per  cent. 

(F)  Boiler  feed  pump     .        v        .  0-9  per  cent. 

(G)  Injector  .         .  •      .,        .         .  None. 

(H)  Water  softening  .  .  .  0-2  per  cent. 
(I)  Economiser  scrapers  .  .  0*2  per  cent. 
(J)  Any  other  auxiliary  steam  .  None. 

Total    .  .         .      12-95  per  cent. 

(K)  Remarks          ....     Enormous  amount  of  steam  being 

taken  by  the  steam  jets. 


DESIGN  OF  REPORT  SHEETS 


TABULATED  RESULTS. 

31.  Water  evaporated  per  Ib.  fuel,  as 

fired 6-60  Ibs. 

32.  Equivalent  evaporation    of  water 

from  and  at  212°    F.  per    Ib. 

fuel,  as  fired     .         .         .         .7-52  Ibs. 

33.  Equivalent  evaporation!  of  water 

from  and  at  212°  F.,  evapor- 
ated per  1,000,000  B.Th.U.  in 
fuel,  as  fired  .  .  .  .641-9  Ibs. 


34.  EFFICIENCY  OF  PLANT. 

(A)  Net  working  thermal  efficiency 

of  the  plant  after  deducting 
the  steam  or  power  used 
auxiliary  to  the  production 
of  steam  corresponding  to 
12-95  Per  cent,  of  the  total 
steam  production  of  the  plant 

(B)  Percentage   of    total   heat   ab- 

sorbed by  the  boiler     . 

(C)  Percentage   of    total   heat   ab- 

sorbed by  the  economiser     . 

(D)  Percentage  of  total   heat   ab- 

sorbed by  the  superheater     . 


57-20  per  cent. 


52-31  per  cent. 


10-02  per  cent. 


3-37  per  cent. 


35.  COST  IN   FUEL   FOR   THE   EVAPORATION  OF   10,000 
LBS.  WATER  .         .         .     365-3  pence. 


36.  LONG  CHECK  TEST. 

(A)  Duration  (hours)      .         .         .  165-00  hours. 

(B)  Dates  and  times        .  '       .         .  — 

(C)  Quality  of  fuel  used  .         .  Small  slack. 

(D)  Price  of  fuel  used     .         .         .  £2  55.  per  ton. 

(E)  Amount  of  fuel  used,  tons         .  110-58. 

(F)  Analysis  of  fuel  used  : — 

(F i )  B.Th.U.  (net  calculated)      .  11,900. 

(F2)  Ash I  ij  per  cent. 

(G)  Total    net    amount    of    water 

evaporated  ....  162,040  Ibs. 


152 


BOILER  PLANT  TESTING 


(H)  Approximate  average  tempera- 
ture of  inlet  water 

(I)  Water  evaporated  per  Ib.  coal  . 

(J)  Cost  in  fuel  to  evaporate  1000 
gallons  of  water  . 

(K)  Approximate  annual  coal  bill  *5f 
the  plant 

(L)  Remarks. 


120°  F. 
6-54  Ibs. 

368  6  pence. 


Week's  results  would  be  expected 
to  be  like  the  day's  test  since 
the  plant  works  day  and  night. 


53 


SUMMARY. 

IN  summing  up  the  whole  question  of  boiler  plant  testing 
I  should  like  to  emphasise  again  that  the  first  necessity  of  any 
International  Code  is  that  it  must  be  practical,  consistent  with 
reasonable  accuracy,  so  that  testing  of  boiler  plant  can  be 
carried  out  regularly  all  the  year  round. 

Such  a  code  in  my  opinion  should  include  the  following, 
as  already  discussed  in  detail  : — 

1.  The  separation  of  boiler  plant  testing  from  every  other 
form  of  testing,  especially  that  of  steam  engines. 

2.  The  duration  of  the  test  to  be  8*0  hours,  and  longer  if 
possible,  six  hours  to  be  allowed  if  peculiar  local  conditions 
demand  it,  but  no  test  to  be  less  than  this. 

3.  In  every  case  a  long  check  test  of  one  week  (168  hours) 
or  longer,  to  be  essential,  so  as  to  include  night  and  week-end 
performances. 

4.  The  dried  fuel  to  be  analysed  in  a  bomb  calorimeter 
and  a  calculated  heat  value  be  taken  based  on  the  percentage 
of  water  and  taking  the  temperature  of  the  boiler  plant  exit 
gases  as  212°  F.     The  determination  of  hydrogen,  with  the 
corresponding  calculated  lower  heat  value,  to  be  abandoned. 

5.  The  use  of  a  CO2  Recorder  for  the  whole  duration  of 
the  trial  to  be  regarded  as  essential. 

6.  The  gases  to  be  analysed  for  CO  and  unburnt  gases, 
either  by  the  use  of  the  "  Duplex  Mono  "  or  by  taking  auto- 
matically a  very  large  sample,  say  20,000  c.c.  at  the  rate  of  at 
least  2000  c.c.  per  hour,  and  analysing  this  sample  with  the 
"  Orsat "  or  other  hand  apparatus. 

7.  In  measuring  the  boiler  feed-water  approved  makes  of 
water  meter  be  allowed,  provided  they  are  fitted  with  a  cali- 
brated test  tank,  or  tested  before  and  after  the  trial. 


154  BOILER  PLANT  TESTING 

8.  The   determination  of  the  moisture   in   the   steam   be 
abandoned  until  reliable  methods  are  discovered. 

9.  The  specific  heat  of  superheated  steam  be  taken  accord- 
ing to  Knoblauch  and  Jakob's  work  and  the  figure  of  0*48  be 
disregarded. 

10.  All   the   steam    used    auxiliary  to  the  production   of 
steam  must  be  determined  with  great  care,  and  deducted  in 
calculating  the  efficiency.      In  the  case  of  steam  jets,  either  a 
steam  meter  or  some  form  of  surface  condenser  to  be  used. 

1 1.  The  new  figure  of  "  Ibs.  of  water  from  and  at  212°  F. 
per  1,000,000  B.Th.U."  be  included  in  the  test  figures. 

12.  The  method  of  calculating  the  results  shall  be  essen- 
tially from  the  heat  of  the  fuel,  and  not  by  the  "  heat  balance 
sheet "  method  based  on  the  flue  gas  analysis. 

The  general  testing  methods  in  vogue  in  the  world  to-day 
are  academic  and  unpractical,  although  very  few  tests  indeed 
can  ever  have  been  carried  out  according  to  the  "Civils" 
Code. 

Certainly  most  of  the  boiler  plants  of  Great  Britain  are 
small,  say  two  or  three  "  Lancashire  "  boilers,  yet  an  Inter- 
national Code  must  be  applicable  to  all  plants,  no  matter 
how  large,  and  the  larger  the  plant  the  more  urgent  is  the 
necessity  for  continual  testing.  The  impossibility  of  the 
"  Civils "  Code  methods  is  best  represented  by  taking  an 
average  fairly  large-sized  factory  boiler  plant,  of,  say,  ten 
"  Lancashire  "  boilers  burning  10,000  tons  of  coal  per  annum, 
with  a  fairly  complete  array  of  accessories  in  the  way  of 
economisers  and  mechanical  stokers,  but  without  superheaters, 
and  with  two  different,  high  and  low,  boiler  pressures. 

In  the  first  place,  the  instructions  are  to  insert  steam  driers 
in  the  steam  pipe  circuit  of  the  plant,  and  then  to  determine 
the  moisture  in  the  steam.  This  means  on  the  given  plant, 
with,  say,  two  8-in.  steam  mains,  high  pressure  and  low 
pressure,  that  the  whole  factory  must  be  shut  off,  whilst  two 
lengths  of  the  main  steam  pipes  are  taken  down  and  two  8-in. 


SUMMARY  155 

steam  driers  fixed  in  the  circuits,  with  special  "  making-up  " 
pieces,  a  formidable  job  itself.  Huge  water  tanks  to  measure 
the  feed-water  have  to  be  carted  in,  and  in  most  cases  the 
greater  part  of  the  boiler  feed  pipe  circuit  will  have  to  be  dis- 
mantled to  fit  in  the  tanks.  If  we  are  to  assume  that  definite 
instructions  are  given  to  determine  the  amount  of  steam  used 
by  the  1 50  or  so  steam  nozzles  of  the  mechanical  stokers, 
then  either  apparently  all  the  small  steam  pipes  supplying 
these  stokers  are  to  be  dismantled  and  a  fresh  steam  pipe 
circuit  connected  up  to  one  of  the  boilers,  which  has  to  be 
tested  separately,  and  the  evaporation  measured,  or  else  each 
of  the  nozzles  must  be  measured  for  area  and  a  crude  empiri- 
cal formulae  used.  That  is  to  say,  there  are  really  two  boiler 
tests,  which  means  a  separate  smaller  set  of  water  measuring 
tanks.  In  addition  to  this,  samples  of  flue  gas  have  to  be 
taken  in  small  tubes  filled  with  mercury,  and  a  continual 
series  of  CO2  analysis  carried  out  by  "Orsat"  apparatus,  and 
at  the  beginning  and  end  of  the  trial  every  one  of  the  twenty 
fires  has  to  be  measured  for  thickness  by  means  of  the  "  tools  " 
already  discussed.  Then  there  is  a  complete  chemical 
analysis  of  various  samples  of  coal  to  be  carried  out,  that  is, 
the  determination  of  the  carbon,  oxygen,  hydrogen,  etc.,  in 
addition  to  the  heating  value  by  means  of  a  bomb  calorimeter. 

Such  a  test  would  dislocate  the  usual  working  of  the  boiler 
plant  for  at  least  a  month,  and  on  the  actual  test  at  least  a 
dozen  trained  observers  would  be  required,  whilst,  as  an  anti- 
climax, three  hours  is  sufficient  for  the  test !  It  is  therefore 
not  to  be  wondered  at  that  boiler  tests  are  not  carried  out 
according  to  the  "  Civils  "  Code,  and  that  boiler  testing  is  not 
popular  when  such  methods  are  regarded  as  necessary. 

It  should  be  the  endeavour  of  an  International  Code  to 
avoid  such  mistakes.  We  have  got  to  remember  that  there 
must  always  be  a  considerable  margin  of  error.  Thus  the 
coal  and  water,  whether  by  mechanical,  or  laborious  hand 
means,  cannot  be  weighed  to  within  I  per  cent,  of  absolute 
accuracy,  and  certainly  the  percentage  of  CO2  cannot  be 


156  BOILER  PLANT  TESTING 

determined  to  within  -J  per  cent.,  if  only  because  of  the  diffi- 
culty of  obtaining  a  true  average  sample.  It  is  therefore  no 
use  going  to  a  lot  of  trouble  over  points  that  are  of  no  practi- 
cal importance,  and  what  is  necessary  is  to  concentrate  par- 
ticularly on  the  points  that  matter,  such  as  the  weight  of  the 
water  evaporated,  the  weight  of  the  coal  used,  the  proper 
sampling  and  analysis  of  the  fuel,  and  the  auxiliary  steam  or 
power. 

I  am  sure  that  the  combined  experience  of  American, 
British  and  French  engineers,  who  have  had  actual  practical 
experience  of  boiler  plant  testing  would  soon  formulate  a 
practical  and  accurate  International  Code  which  would  be  of 
immense  benefit  to  the  engineering  profession  in  all  the 
countries  concerned,  and  if  this  book  is  a  help  towards  such 
a  deserving  object  its  success  will  have  been  achieved. 


157 


INDEX. 


Ados  CO2  recorder,  68. 

Albion  CO2  recorder,  68. 

American  boiler  plants,  efficiency  of,  48. 

American  Society  of  Mechanical  Engineers — 

Address,  Introduction,  vi. 

Auxiliary  steam  or  power,  94,  99. 

Coal  analysis,  56,  57. 

Duration  of  test,  53. 

Feed-water  measurement,  81,  82. 

Flue  gas  analysis,  68. 

Fuel  calorimeter  recommended,  57. 

History  of  test  Code,  Introduction,  vi. 

Moisture  in  steam,  88,  90-91. 

Separate  boiler  testing  Code,  necessity  of,  49-50. 

Testing  water  meters,  86,  87. 
Analysis  of  coal.     See  Coal  analysis. 

feed-water.     See  Feed-water. 

flue  gases,  automatic.     See  Flue  gas. 

hand.     See  Flue  gas. 

Andre,  evaporative  figures  of  different  coals,  3. 
Ash,  methods  of  analysis  used  in  the  author's  tests,  9. 
—  data  suggested  for  International  Code,  147. 
— •  handling,  mechanical,  steam  or  power  used,  96,  97,  99. 
Attendance,  suggestion  to  include  in  test  calculations,  127  130. 
Auto  CO2  recorder,  68. 
Automatic  gas  analysis.     See  Flue  gas. 
A  very  automatic  water  weigher,  83. 


Bailey  steam  meter,  132. 
—  water  meter  C-4,  84. 
V  Notch,  83. 


158  BOILER  PLANT  TESTING 

Barometer,  question  of  reading  for  tests,  111-112. 

Barrus  calorimeter,  57. 

Bayer  steam  meter,  132. 

Berthelot-Mahler  fuel  calorimeter,  57. 

Bimeter  CO2  recorder,  68. 

Black  smoke,  148. 

Boiler,  calculations^  suggested  for  heat  absorption,  118. 

—  Cornish.     See  Boilers,  small  cylindrical. 

—  data  for  suggested  International  Code,  135. 

—  egg-ended,  number  still  at  work,  15. 

typical  performance  figures,  35. 

—  feed-pump.     See  Pumps. 

—  feed-water.     See  Feed-water. 

—  Lancashire,  typical  performance  figures,  20-27. 

—  small  cylindrical,  typical  performance  figures,  30-32. 

—  test  Codes.     See  Civils  Code. 

See  American  Society  of  Mechanical  Engineers. 

—  vertical,  typical  performance  figures,  32-33. 

—  water  tube,  typical  performance  figures,  26-30. 
Brame,  J.  S.  S.,  figures  for  hydrogen  in  coal,  57-58. 
Breckenridge,  methods  of  flue  gas  analysis,  75. 
British-Thomson  Houston  steam  meter,  132. 

water  meter,  84. 


Calculations,  115-123. 

—  author's  methods  for  heat  value  of  fuel,  8. 

—  chimney  draught,  43. 

—  criticism  of  Civils  Code  methods,  121-123. 

-  efficiency  figures  suggested,  International  Code,  151. 

—  factor  for  the  diminishing  heat  value  of  the  coal,  124-128. 

—  heat  absorbed  by  the.  boiler,  118. 

—  heat  absorbed  by  the  economiser,  118. 

-  heat  absorbed  by  the  superheater,  119. 

—  Ibs.  water  from  and  at  212  F.,  119. 

—  improved  methods  suggested,  115-120. 

—  nett  working  efficiency,  119. 

—  saving  in  coal  bill,  economisers,  120. 

superheaters,  120. 

—  suggestions  to  include  labour,  attendance,  repairs,  upkeep,  in- 

terest, and  depreciation,  127-130. 
Calorimeter,  fuel,  Barrus,  57. 

Berthelot-Mahler,  57. 

Mahler-Cook,  57. 


INDEX  1 59 

Calorimeter,  fuel,  Mahler-Donkin,  8,  57. 
gross  and  nett  heating  value,  57-64 . 

—  necessity  of  bomb  type,  56. 

recommendations  of  American  Code,  57. 

—  —  recommendations  of  Civils  Code,  57. 
Calorimeter,  steam,  difficulties  in  the  use  of,  88-89. 
Cambridge  Electrical  CO2  recorder,  69. 

Carbon  dioxide.     See  CO2. 

—  monoxide,  theory  of  in  flue  gas,  65-67. 

Chemical  works,  efficiency  figures  for  sixty  boiler  plants,  15. 
Chimney,  data  suggested  for  International  Code,  139. 

—  draught.     See  Draught. 

Civils  Code,  address  for  Code,  Introduction,  vi. 

auxiliary  steam  or  power,  94-99. 

— •  calorimeter  (fuel)  recommended,  57. 

—  coal  analysis,  56-57. 

—  duration  of  test,  52. 

—  feed -water  measurement,  80-8 1. 

— •  flue  gas  analysis,  methods,  68,  73-74. 

•  history  of  Code,  Introduction,  vi. 

— •  moisture  in  steam,  88-89. 

—  object  of  boiler  plant  testing,  51-52. 

separate  boiler  testing  Code,  necessity  of,  49-50. 

specific  heat  of  superheated  steam,  92-94. 

—  thickness  of  fires,  112-114. 

CO2,  curve  showing  fuel  loss  at  all  percentages,  72. 

—  figures  for  250  boiler  plants,  n. 

—  . 400  boiler  plants,  71-72. 

Lancashire  boiler  plants,  23. 

water-tube  boiler  plants,  29. 

small  cylindrical  boiler  plants,  31. 

— •  vertical  boiler  plants,  33. 
egg-ended  boiler  plants,  35. 

—  theory  of,  in  flue  gases,  65. 

-  recorders,  accuracy,  method  of  testing,  69. 
Ados,  68. 

Albion,  68. 

American  Society  of  Mechanical  Engineers,  remarks,  68. 

-  Auto,  68. 

—  Bimeter,  68. 

-  Cambridge  electrical,  69. 
Civils  Code,  remarks,  68. 

Duplex  mono,  66-69. 

Hay's,  69. 


160  BOILER  PLANT  TESTING 

CO2,  recorders,  methods  used  by  the  author,  70-71. 

—  —  Mono,  67. 
Sarco,  68. 

—  —  Simmance-Abady,  68. 

-  Ward,  68. 

—  —  W.R.  indicator;  69. 
Coal  analysis,  57-64-. 

American  Society  of  Mechanical  Engineers,  56. 

Civils  Code,  remarks,  56. 

-  curve  showing  deduction  for  hydrogen,  6$. 
data  suggested  for  International  Code,  147. 

—  —  gross  and  nett  heating  value,  57-64. 

-  hydrogen,  suggestion  to  abandon  determination,  61-63. 
methods  used  in  the  author's  tests,  7. 

—  —  moisture,  average  figures  for,  57. 

-  necessity  of  bomb  calorimeter,  56. 
—  recommendations  by  the  author,  61. 

-  sampling  of  coal,  56. 

—  —  See  also  Calorimeters,  fuel. 

-  consumption  in  Great  Britain,  38. 

—  mechanical  handling,  steam  or  power  used,  96,  97,  99. 
Codes,  boiler  test.     See  American  Mechanical  Engineers. 
See  Civils  Code. 

Collieries,  performance  figures  for  100  boiler  plants,  14. 

Combustion,  critical  point  of  efficient,  67. 

Cornish  boiler.     See  Boilers. 

Corrosion,  electrolytic  anti-process,  steam  or  power  used,  96,  97,  no. 

Curnon  steam  meter,  132. 

Curve,  efficiency  for  diminishing  heat  value  of  coal,  128. 

-  CO2,  showing  fuel  loss  at  all  percentages,  72. 

-  hydrogen  in  coal,  calculations,  63. 

-  specific  heat  of  water,  117. 

—  superheated  steam,  Knoblauch  and  Jakob,  93. 
Cylindrical  boilers.     See  Boilers. 


D 

Depreciation,  suggestion  to  include  in  test  calculations,  127-130. 
Donkin,  Bryan,  results  of  boiler  tests,  2. 

-  and  A.  B.  W.  Kennedy,  results  of  boiler  tests,  4. 
Draught,  calculations  for  chimney  draught,  40. 
—  chimney,  disadvantages  of,  43. 

-  choking  by  economisers,  43. 

-  data  suggested  for  International  Code,  148. 


INDEX  161 

Draught,  figures  for  Lancashire  boiler  plant,  21-22. 

-  water-tube  boiler  plant,  26-28. 

-  small  cylindrical  boiler  plant,  31. 

-  vertical  boiler  plant,  33. 
—  egg-ended  boiler  plant,  35. 

-  forced,  advantages  of,  45. 

-  amount  of  steam  or  power  taken,  45,  96,  97,  no. 

-  induced,  advantages  of,  45. 

-  amount  of  steam  or  power  taken,  45,  96,  97,  no. 

-  mechanical,  data  suggested  for  International  Code,  140-142. 

-  figures  for  use  in  Great  Britain,  43. 

-  method  of  measurement  used  by  the  author,  10. 
Driers,  steam.     See  Steam. 

Duplex-mono  flue  gas  analysing  machine,  66-69. 
Duration  of  test,  general  consideration,  52-56. 

-  American  Mechanical  Engineers,  remarks,  53. 

-  Civils  Code,  remarks,  52. 

-  long  check  test,  54-55. 

-  suggestions  by  the  author,  54. 
Dust  in  chimney  gases,  54. 

Dyeing,  etc.,  industry,  performance  figures  for  sixty-five  boiler  plants, 
17-18. 

E 

Economisers,  calculation  for  heat  absorbed  by,  118. 

-  calculation  for  fuel  saving,  120. 

-  choking  of  draught  by,  43-44. 

-  data  suggested  for  International  Code,  138-139. 

-  figures  for  250  boiler  plant  tests,  40. 
—  —  Lancashire  boiler  plant,  24. 

-  water-tube  boiler  plant,  29. 

-  national  loss  through  lack  of,  41. 

-  steam  or  power  used  by  the  scraper  drive,  96,  97,  no. 

-  sweating,  60. 

Efficiency,  American  boiler  plants,  48. 

-  British  boiler  plants,  39. 

-  chemical  works,  sixty  boiler  plants,  15. 

-  collieries,  100  boiler  plants,  14. 

-  cylindrical  boilers,  small,  31. 

-  dyeing,  etc.,  industry,  sixty-five  boiler  plants,  17. 

-  egg-ended  boiler  plants,  35. 

-  French  boiler  plants,  48. 

-  Lancashire  boiler  plants,  21,  25. 

-  mechanical  stoker  plants,  42. 

II 


1 62  BOILER  PLANT  TESTING 

Efficiency,  250  typical  steam  boiler  plants,  18-19. 

—  400  typical  steam  boiler  plants,  12. 

-  vertical  boiler  plants,  32-33. 

-  water-tube  boiler  plants,  26,  30. 

—  See  also  Calculations. 
Egg-ended  boilers.     See  Boilers.  ,» 

Electrolytic  anti-corrosion  methods,  steam  or  power  used,  96,  97,  no. 


Factor  for  the  diminishing  heat  value  of  fuel,  124-127. 
Feed -water,  analysis,  methods  used  by  the  author,  10. 

-  average  figures  for  Great  Britain,  41. 

-  figures  for  Lancashire  boiler  plants,  23. 

-  water-tube  boiler  plants,  29. 

-  measurement,  American  Code,  remarks,  81-82. 

-  Civils  Code,  remarks,  80-8 1. 

-  data  suggested  for  International  Code,  142-144. 

-  tank  method,  80-81. 

-  See  also  Meters,  water. 
Firing,  hand.     See  Hand  firing. 

-  Mechanical.     See  Mechanical  firing. 

Flues,  data  suggested  for  International  Code,  137,  139,  148. 
Flue  gas  analysis,  64-80. 

-  Automatic.     See  CO2  recorders. 

-  Civils  Code,  calculations  based  on,  121-122. 

-  methods  suggested,  68-76. 

-  permanent  installation  recommended,  75. 

-  data  suggested  for  International  Code,  137,  139,  148. 

-  hand  methods,  76-78. 

-  heat  balance,  78. 

-  methane,  presence  of,  65. 

-  principle  of  the  methods  used,  66. 

-  sulphur  dioxide,  presence  of,  65. 

-  theory  of,  65. 

-  temperatures.     See  Temperature. 
Forced  Draught.     See  Draught. 
French  boiler  plants,  efficiency  of,  48. 
Fuel  analysis.     See  also  Calorimeters,  fuel. 

-  See  Coal  analysis. 
—  sampling,  56. 

Furnaces,  steam  jet.     See  Steam  jets. 


INDEX  163 


Goodenough,  G.  A.,  specific  heat  of  superheated  steam,  92. 
Grit  in  chimney  gases,  130-131. 
Gross  heating  value  of  fuel,  57-64. 

H 

Hand  firing,  results  in  comparison  with  mechanical,  42. 
Hay's  CO2  recorder,  69. 

-  flue  gas  collector,  76-78. 

Heat  balance  sheet  method  of  calculation,  79. 
Hempel  gas  analysis  apparatus,  68. 
Hirn's  formulae,  specific  heat  of  superheated  steam,  93. 
Huntly,  G.  Nevil,  flue  gas  analysis,  73-74. 

Hutton,  W.  S.,  performance  figures  for  different  types  of  boiler,  2. 
Hydrogen,    author's    suggestion    to    abandon    determination    of   in 
coal,  63. 

-  Brame,  J.  S.  S.,  figures  for  coal  constitution,  57-58. 

-  curve  showing  effect  on  heat  value  of  coal,  63. 

-  flue  gas,  presence  in,  65. 


Ingenieurs  Civils  de  France,  Introduction,  vi. 
Institution  of  Chemical  Engineers,  Introduction,  vi. 

-  Civil  Engineers.     See  Civils. 

-  Electrical  Engineers,  Introduction,  vi. 

-  Mechanical  Engineers,  Introduction,  vi. 

-  Mining  Engineers,  Introduction,  vi. 

Interest,  suggestion  to  include  in  boiler  test  calculations,  127-130. 

K 

Kennedy  water  meter,  83. 

-  A.  B.  W.,  boiler  tests,  4. 

Kent  displacement  type  water  meter,  84. 

-  V  Notch  water  meter,  83. 

-  steam  meter,  132. 

Kempe,  performance  of  boiler  plant,  4. 

Knoblauch  and  Jakob,  specific  heat  of  superheated  steam,  93. 


Labour,  suggestions  to  include  in  test  calculations,  127-130. 
Lancashire  boiler.     See  Boilers. 


1  64  BOILER  PLANT  TESTING 

Latent  heat  of  steam.     See  Steam. 
Lea  V  Notch  water  meter,  83. 
Leinert  water  meter,  83. 


M 

"         •  jit 

Mahler-Cooke  fuel  calorimeter,  57. 

Mahler-Donkin  fuel  calorimeter,  57. 

Mechanical  coal  and  ash  handling,  data  suggested  for  International 

Code,  135. 

-  steam  or  power  used,  96,  97,  99. 
Mechanical  draught.     See  Draught. 

-  stoking,  data  suggested  for  International  Code,  136. 

-  figures  for  the  performance  of  eighty  boiler  plants,  42. 

—  national  coal  bill  of,  42. 

—  steam  or  power  used  by,  96,  97,  99. 

-  steam  used  by  steam  jets.     See  Steam  jets. 
Meters,  steam,  American  Mechanical  Engineers,  101-103. 

—  Bailev,  132. 

-  Bayer,  132. 

—  British-Thomson  Houston,  132. 

—  Curnon,  132. 

—  data  suggested  for  International  Code,  146. 

-  Kent,  132. 

-  St.  John,  132. 

-  —  Sarco,  132.  , 

—  water,  American  Mechanicals  Code,  81-82. 
--  Avery  ^automatic  water  weigher,  83. 

-  Bailey  fluid  meter  C4,  84. 
—  V  Notch  meter,  83. 

--  Civils  Code,  remarks,  80-81. 

-  data  suggested  for  International  Code,  145. 

-  Kennedy  meter,  83. 

---  Kent  displacement  meter,  84. 

--  V  Notch  meter,  83. 
---  Lea  V  Notch  recorder,  83. 

—  —  Leinert  meter,  83. 
--  Paterson  fluxograph,  83. 

--  Rheograph  water  flow  recorder,  83. 

--  Sarco  disc  meter,  84. 

---  piston  meter,  83. 

---  tippling  meter,  83. 

•  --  Siemans'  disc  meter,  84. 

---  and  Adamson  meter,  84. 

--  Simmance-Abady  precision  meter,  83. 


INDEX  165 


Meters,  testing,  American  Mechanical  Engineers,  86-87. 
-  methods  suggested  by  the  author,  85-86. 

-  Worthington  duplex  meter,  83. 

turbine  meter,  84. 

-  Venturi  meter,  80,  82,  84. 
Methane  in  flue  gas,  65. 

Moisture  in  coal,  average  figures,  57. 

—  steam.     See  Steam. 

Molesworth,  performance  figures  for  boilers,*3. 
Mono,  CO  automatic  gas  analysing  machine,  69. 

-  CO.,  recorder,  67. 


N 


Nett  heating  value  of  coal,  57-64. 

—  working  efficiency  of  boiler  plant,  119. 


0 


Object  of  boiler  plant  testing,  57. 

Orsat  apparatus,  general  principle  of,  66. 

Civils  Code,  remarks,  74. 


Papermaking  industry,  performance  figures  of  forty  boiler  plants,  18. 
Paterson  fluxograph  water  meter,  83. 

Pounds  of  water  from  and  at  212  F.  per  1,000,000  B.Th.U.,  in. 
Pumps,  boiler-feed,  steam  or  power  used,  96,  97,  no. 

data  suggested  for  International  Code,  144. 

Pyrometers.     See  Temperature. 


R 

Radiation,  tests  for  losses  by  on  boiler  plant,  120-121. 
Regnault  and  Hirn,  specific  heat  of  superheated  steam,  93. 
Repairs,  suggestions  to  include  in  boiler  test  calculations,  127-130. 
Rheograph  flow  water  meter,  83. 


St.  John  steam  meter,  132. 
Sampling  fuel,  56. 
—  steam,  89-90. 


1 66  BOILER  PLANT  TESTING 

Sarco  CO2  recorder,  68. 

-  disc  water  meter,  84 . 

-  piston  water  meter,  83. 

-  steam  meter,  132. 

-  tippling  water  meter,  83. 
Siemans'  disc  water  meter,  84.    ^ 

-  and  Adamson  water  meter,  £4. 
Simmance-Abady  CO2  recorder,  68. 

-  precision  water  meter,  83. 

Society  of  Chemical  Industry,  Introduction,  vi.  ' 
Specific  heat  of  water.     See  Water. 

-  superheated  steam.     See  Steam. 
Steam,  auxiliary,  94-111. 

American  Society  of  Mechanical  Engineers,  99. 
boiler-feed  pumps,  96,  97,  no. 
Civils  Code,  remarks,  95-99. 
data  suggested  for  International  Code,  150. 
drawing  showing  'the  various  items,  96-97. 
Economiser  engine,  96,  97,  no. 
electrolytic  anti-corrosion,  96,  97,  no. 
figures  for  Lancashire  boiler  plants,  25. 

coal  and  ash  handling,  96,  97,  99. 
mechanical  draught,  96,  97,  no. 
mechanical  stoking,  96,  97,  99. 
steam  jets.     See  Steam  jets, 
water-softening  plant,  96,  97,  no. 
water-tube  boiler  plant,  29. 

-  calorimeters.     See  Calorimeters. 

-  Driers,  Civils  Code,  remarks,  89. 

-  Stefco,  89. 

-  Tracy,  89. 

-  generation,  figures  for  coal  consumption  of  Great  Britain,  38. 

-  jets,  45-47,  loo-no. 

-  determination  of,  American  Society  of  Mechanical  Engineers, 

IOI-I02. 

-  Civils  Code,  100,  109,  no. 

-  cold  water  method,  109. 

-  gauge  glass  method,  102. 

-  method  used  by  the  author,  107-109. 

-  steam  meters,  American  Code,  103. 

-  author's  suggestion,  103. 

-  figures  for  250  boiler  plants,  45. 

hand-fired  furnaces,  46. 
mechanical  stokers,  46. 
in  detail  of  153  boiler  tests,  104-107. 


INDEX  167 

Steam  jets,  number  of  plants  in  Great  Britain  fitted,  47. 

-  latent  heat,  different  figures  in  use,  112. 

-  meters.     See  Meters. 

-  moisture  in,  9,  88-92. 

-  American  Society  of  Mechanical  Engineers,  88. 

-  Civils  Code,  88. 

-  figures  for  average  conditions,  88. 

-  methods  of  sampling,  89-90. 

-  recommendations  by  the  author,  91-92. 

-  Unwin's  paper,  89. 
—  See  also  Steam  driers. 

-  pressure,  average  figures  for  Great  Britain,  1 1 . 

-  specific  heat  of,  92-94. 

-  Civils  Code,  remarks,  92. 

-  Good  enough,  92. 

-  Knoblauch  and  Jakob's  curves,  93. 

-  Regnault  and  Hirn,  93. 

-  superheated.     See  Superheated  steam. 

-  tables,  Marks  and  Davis,  92. 
Stefco  steam  drier,  89. 
Stoking,  hand.     See  Hand -firing. 

-  mechanical.     See  Mechanical  stoking. 
Sulphur  dioxide  in  flue  gases,  65. 

Superheated  steam,  calculations,  heat  absorbed  by  superheater,  119. 

saving  in  coal  bill,  120. 

data  suggested  for  International  Code,  145-150. 
figures  for  250  boiler  plants,  48. 

Lancashire  boiler  plants,  24. 
water -tube  boiler  plants,  29. 
national  fuel  loss  through  lack  of,  48. 
specific  heat,  92-94. 
Svenska  Aktiebolaget  Mono.     See  Duplex  mono. 


Tank  method  of  measuring  feed-water.     See  Feed-water. 
Temperature,  feed-water,  Civils  Code,  remarks,  112. 

data  suggested  for  International  Code,  149. 

figures  for  250  boiler  plants,  10. 

use  of  oil,  112. 
-  flue  gases,  Civils  Code,  remarks,  112. 

-  data  suggested  for  International  Code,  147-148. 

-  electric  resistance  pyrometers,  10. 

-  figures  for  250  tests,  10. 


1 68  BOILER  PLANT  TESTING 

Test  codes.     See  American  Society  of  Mechanical  Engineers. 
—  Civils  Code. 

sheets,  suggestions  for  International  Code,  133-152. 
Testing  of  water  meters,  85-87. 

Thickness  of  fires,  Civils  Code  instructions,  112-114. 
Tracy  steam  drier,  89. " 


U 

Upkeep,  suggestions  to  include  in  boiler  test  calculations,  127-130. 
Unwin,  Dr.  W.  C.,  moisture  in  steam,  89. 


Venturi  meters,  80,  82-84. 
Vertical  boilers.     See  Boilers. 


W 

Ward  CO2  recorder,  68. 

Water-softening,  average  figures  for  Great  Britain,  41. 

—  data  suggested  for  International  Code,  143. 

—  steam  or  power  used  by,  96,  97,  no. 
Water,  specific  heat,  Civils  Code  figures,  116-117. 

curve  for  varying  temperatures,  117. 

formulae  recommended  by  the  author,  117. 
Water-tube  boilers.     See  Boilers. 
W.R.  combustion  indicator,  69. 
Worthington  duplex  water  meter,  83. 

—  turbine  water  meter,  84. 


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